1
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Maniv A, Reyes AP, Ramakrishna SK, Graf D, Huq A, Potashnikov D, Rivin O, Pesach A, Tao Q, Rosen J, Felner I, Caspi EN. Microscopic evidence for Mn-induced long range magnetic ordering in MAX phase compounds. J Phys Condens Matter 2021; 33:025803. [PMID: 32942268 DOI: 10.1088/1361-648x/abb998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Zero and low field nuclear magnetic resonance measurements have been performed on MAX phase samples (Cr1-x Mn x )2AC with A = Ge and Ga in order to obtain local microscopic information on the nature of magnetism in this system. Our results unambiguously provide evidence for the existence of long-range magnetic order in (Cr0.96Mn0.04)2GeC and for (Cr0.93Mn0.07)2GaC, but not for (Cr0.97Mn0.03)2GaC. We point to a possible dependence of long range magnetic order in these MAX phase compounds on the A atom.
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Affiliation(s)
- A Maniv
- Department of Physics, Nuclear Research Center-Negev, PO Box 9001, Beer Sheva 84190, Israel
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States of America
| | - A P Reyes
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States of America
| | - S K Ramakrishna
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States of America
| | - D Graf
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, United States of America
| | - A Huq
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States of America
| | - D Potashnikov
- Faculty of Physics, Technion-Israeli Institute of Technology, Haifa 32000, Israel
- Israel Atomic Energy Commission, PO Box 7061, Tel-Aviv 61070, Israel
| | - O Rivin
- Department of Physics, Nuclear Research Center-Negev, PO Box 9001, Beer Sheva 84190, Israel
| | - A Pesach
- Department of Physics, Nuclear Research Center-Negev, PO Box 9001, Beer Sheva 84190, Israel
| | - Q Tao
- Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Linkoping, Sweden
| | - J Rosen
- Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Linkoping, Sweden
| | - I Felner
- Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - E N Caspi
- Department of Physics, Nuclear Research Center-Negev, PO Box 9001, Beer Sheva 84190, Israel
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2
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Abstract
We present in this paper the results from a recent study on the stability of the quantum Hall skyrmions state at a Landau level filling factor (ν) close to ν = 1 in a narrow GaAs quantum well. Consistent with previous work, a resonant behavior is observed in the resistively detected NMR measurements. In the subsequent current-voltage (I-V) measurements to examine its breakdown behavior under radio frequency radiations, we observe that the critical current assumes the largest value right at the 75As nuclear resonant frequency. We discuss possible origin for this unexpectedly enhanced stability.
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Affiliation(s)
- W Pan
- Sandia National Laboratories, Livermore, California, USA.
| | - J L Reno
- Sandia National Laboratories, Albuquerque, New Mexico, USA
| | - A P Reyes
- National High Magnetic Field Laboratory, Tallahassee, Florida, USA
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3
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Kawasaki S, Li Z, Kitahashi M, Lin CT, Kuhns PL, Reyes AP, Zheng GQ. Charge-density-wave order takes over antiferromagnetism in Bi 2Sr 2-x La x CuO 6 superconductors. Nat Commun 2017; 8:1267. [PMID: 29097672 PMCID: PMC5668353 DOI: 10.1038/s41467-017-01465-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/19/2017] [Indexed: 11/17/2022] Open
Abstract
Superconductivity appears in the cuprates when a spin order is destroyed, while the role of charge is less known. Recently, charge density wave (CDW) was found below the superconducting dome in YBa2Cu3Oy when a high magnetic field is applied perpendicular to the CuO2 plane, which was suggested to arise from incipient CDW in the vortex cores that becomes overlapped. Here by 63Cu-nuclear magnetic resonance, we report the discovery of CDW induced by an in-plane field, setting in above the dome in single-layered Bi2Sr2−xLaxCuO6. The onset temperature TCDW takes over the antiferromagnetic order temperature TN beyond a critical doping level at which superconductivity starts to emerge, and scales with the pseudogap temperature T*. These results provide important insights into the relationship between spin order, CDW and the pseudogap, and their connections to high-temperature superconductivity. Whilst superconductivity usually appears when magnetic order is suppressed, the role of charge is less known. Here, Kawasaki et al. report a charge density wave (CDW) above the superconducting transition induced by an in-plane magnetic field in Bi2Sr2-xLaxCuO6, with the CDW onset temperature scaling with the pseudogap temperature.
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Affiliation(s)
- S Kawasaki
- Department of Physics, Okayama University, Okayama, 700-8530, Japan
| | - Z Li
- Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter Physics, 100190, Beijing, China
| | - M Kitahashi
- Department of Physics, Okayama University, Okayama, 700-8530, Japan
| | - C T Lin
- Max-Planck-Institut fur Festkorperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
| | - P L Kuhns
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - A P Reyes
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Guo-Qing Zheng
- Department of Physics, Okayama University, Okayama, 700-8530, Japan. .,Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter Physics, 100190, Beijing, China.
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4
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Lu L, Song M, Liu W, Reyes AP, Kuhns P, Lee HO, Fisher IR, Mitrović VF. Magnetism and local symmetry breaking in a Mott insulator with strong spin orbit interactions. Nat Commun 2017; 8:14407. [PMID: 28181502 PMCID: PMC5309813 DOI: 10.1038/ncomms14407] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 12/25/2016] [Indexed: 11/09/2022] Open
Abstract
Study of the combined effects of strong electronic correlations with spin-orbit coupling (SOC) represents a central issue in quantum materials research. Predicting emergent properties represents a huge theoretical problem since the presence of SOC implies that the spin is not a good quantum number. Existing theories propose the emergence of a multitude of exotic quantum phases, distinguishable by either local point symmetry breaking or local spin expectation values, even in materials with simple cubic crystal structure such as Ba2NaOsO6. Experimental tests of these theories by local probes are highly sought for. Our local measurements designed to concurrently probe spin and orbital/lattice degrees of freedom of Ba2NaOsO6 provide such tests. Here we show that a canted ferromagnetic phase which is preceded by local point symmetry breaking is stabilized at low temperatures, as predicted by quantum theories involving multipolar spin interactions.
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Affiliation(s)
- L Lu
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - M Song
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - W Liu
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - A P Reyes
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - P Kuhns
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - H O Lee
- Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - I R Fisher
- Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.,Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - V F Mitrović
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
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5
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Zhou R, Hirata M, Wu T, Vinograd I, Mayaffre H, Krämer S, Horvatić M, Berthier C, Reyes AP, Kuhns PL, Liang R, Hardy WN, Bonn DA, Julien MH. Quasiparticle Scattering off Defects and Possible Bound States in Charge-Ordered YBa_{2}Cu_{3}O_{y}. Phys Rev Lett 2017; 118:017001. [PMID: 28106424 DOI: 10.1103/physrevlett.118.017001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 06/06/2023]
Abstract
We report the NMR observation of a skewed distribution of ^{17}O Knight shifts when a magnetic field quenches superconductivity and induces long-range charge-density-wave (CDW) order in YBa_{2}Cu_{3}O_{y}. This distribution is explained by an inhomogeneous pattern of the local density of states N(E_{F}) arising from quasiparticle scattering off, yet unidentified, defects in the CDW state. We argue that the effect is most likely related to the formation of quasiparticle bound states, as is known to occur, under specific circumstances, in some metals and superconductors (but not in the CDW state, in general, except for very few cases in 1D materials). These observations should provide insight into the microscopic nature of the CDW, especially regarding the reconstructed band structure and the sensitivity to disorder.
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Affiliation(s)
- R Zhou
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - M Hirata
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - T Wu
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - I Vinograd
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - H Mayaffre
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - S Krämer
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - M Horvatić
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - C Berthier
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-UPS-INSA-EMFL, 38042 Grenoble, France
| | - A P Reyes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - P L Kuhns
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - R Liang
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Canadian Institute for Advanced Research, Toronto M5G 1Z8, Canada
| | - W N Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Canadian Institute for Advanced Research, Toronto M5G 1Z8, Canada
| | - D A Bonn
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Canadian Institute for Advanced Research, Toronto M5G 1Z8, Canada
| | - M-H Julien
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-EMFL, 38042 Grenoble, France
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6
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Wu G, Greene RL, Reyes AP, Kuhns PL, Moulton WG, Wu B, Wu F, Clark WG. Superconducting anisotropy in the electron-doped high-Tc superconductors Pr2-xCexCuO4-y. J Phys Condens Matter 2014; 26:405701. [PMID: 25219526 DOI: 10.1088/0953-8984/26/40/405701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report superconducting anisotropy measurements in the electron-doped high-Tc superconductors (HTSCs) Pr(2-x)Ce(x)C(u)O(4-y) (PCCO, x = 0.15 and 0.17) with an applied magnetic field (H0) up to 28 T. Our results show that the upper critical field [H(c2)(T)] of PCCO is highly anisotropic and as the temperature T → 0, the value of it at H0 ∥ c [H(c2,∥c)(0)] is far less than the Pauli limit. The low temperature anisotropic character of PCCO is found to be rather similar to that of hole-doped cuprate HTSCs, but apparently larger than that of typical Fe-based superconductors. This study also proves a new sensitive probe of detecting rich properties of unconventional superconductors with the use of the resonant frequency of an NMR probe circuit.
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Affiliation(s)
- Guoqing Wu
- College of Physics Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225002, People's Republic of China. Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
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7
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Sakai H, Tokunaga Y, Kambe S, Urbano RR, Suzuki MT, Kuhns PL, Reyes AP, Tobash PH, Ronning F, Bauer ED, Thompson JD. Emergent antiferromagnetism out of the "hidden-order" state in URu2Si2: high magnetic field nuclear magnetic resonance to 40 T. Phys Rev Lett 2014; 112:236401. [PMID: 24972218 DOI: 10.1103/physrevlett.112.236401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Indexed: 06/03/2023]
Abstract
Very high field (29)Si-NMR measurements using a fully (29)Si-enriched URu(2)Si(2) single crystal were carried out in order to microscopically investigate the "hidden order" (HO) state and adjacent magnetic phases in the high field limit. At the lowest measured temperature of 0.4 K, a clear anomaly reflecting a Fermi surface instability near 22 T inside the HO state is detected by the (29)Si shift, (29)K(c). Moreover, a strong enhancement of (29)K(c) develops near a critical field H(c) ≃ 35.6 T, and the ^{29}Si-NMR signal disappears suddenly at H(c), indicating the total suppression of the HO state. Nevertheless, a weak and shifted (29)Si-NMR signal reappears for fields higher than H(c) at 4.2 K, providing evidence for a magnetic structure within the magnetic phase caused by the Ising-type anisotropy of the uranium ordered moments.
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Affiliation(s)
- H Sakai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Tokunaga
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - S Kambe
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - R R Urbano
- Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, 13083-859 Campinas, SP, Brazil and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - M-T Suzuki
- CCSE, Japan Atomic Energy Agency, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8587, Japan
| | - P L Kuhns
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - A P Reyes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - P H Tobash
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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8
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Mounce AM, Oh S, Lee JA, Halperin WP, Reyes AP, Kuhns PL, Chan MK, Dorow C, Ji L, Xia D, Zhao X, Greven M. Absence of static loop-current magnetism at the apical oxygen site in HgBa2CuO4+δ from NMR. Phys Rev Lett 2013; 111:187003. [PMID: 24237553 DOI: 10.1103/physrevlett.111.187003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Indexed: 06/02/2023]
Abstract
The simple structure of HgBa(2)CuO(4+δ) (Hg1201) is ideal among cuprates for study of the pseudogap phase as a broken symmetry state. We have performed (17)O nuclear magnetic resonance on an underdoped Hg1201 crystal with a transition temperature of 74 K to look for circulating loop currents proposed theoretically and inferred from neutron scattering. The narrow spectra preclude static local fields in the pseudogap phase at the apical site, suggesting that the moments observed with neutrons are fluctuating. The nuclear magnetic resonance frequency shifts are consistent with a dipolar field from the Cu(2+) site.
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Affiliation(s)
- A M Mounce
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
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9
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Bauer ED, Yang YF, Capan C, Urbano RR, Miclea CF, Sakai H, Ronning F, Graf MJ, Balatsky AV, Movshovich R, Bianchi AD, Reyes AP, Kuhns PL, Thompson JD, Fisk Z. Electronic inhomogeneity in a Kondo lattice. Proc Natl Acad Sci U S A 2011; 108:6857-6861. [PMCID: PMC3084059 DOI: 10.1073/pnas.1103965108] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023] Open
Abstract
Inhomogeneous electronic states resulting from entangled spin, charge, and lattice degrees of freedom are hallmarks of strongly correlated electron materials; such behavior has been observed in many classes of d -electron materials, including the high-T c copper-oxide superconductors, manganites, and most recently the iron–pnictide superconductors. The complexity generated by competing phases in these materials constitutes a considerable theoretical challenge—one that still defies a complete description. Here, we report a manifestation of electronic inhomogeneity in a strongly correlated f -electron system, using CeCoIn5 as an example. A thermodynamic analysis of its superconductivity, combined with nuclear quadrupole resonance measurements, shows that nonmagnetic impurities (Y, La, Yb, Th, Hg, and Sn) locally suppress unconventional superconductivity, generating an inhomogeneous electronic “Swiss cheese” due to disrupted periodicity of the Kondo lattice. Our analysis may be generalized to include related systems, suggesting that electronic inhomogeneity should be considered broadly in Kondo lattice materials.
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Affiliation(s)
- E. D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Yi-feng Yang
- Los Alamos National Laboratory, Los Alamos, NM 87545
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - C. Capan
- Department of Physics and Astronomy, University of California, Irvine, CA 92697
| | - R. R. Urbano
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306
| | - C. F. Miclea
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - H. Sakai
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan; and
| | - F. Ronning
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - M. J. Graf
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | | | - R. Movshovich
- Los Alamos National Laboratory, Los Alamos, NM 87545
| | - A. D. Bianchi
- Department de Physique, Universite de Montreal, Montreal, QC, Canada H3C 3J7
| | - A. P. Reyes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306
| | - P. L. Kuhns
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306
| | | | - Z. Fisk
- Department of Physics and Astronomy, University of California, Irvine, CA 92697
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10
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Mounce AM, Oh S, Mukhopadhyay S, Halperin WP, Reyes AP, Kuhns PL, Fujita K, Ishikado M, Uchida S. Spin-density wave near the vortex cores in the high-temperature superconductor Bi2Sr2CaCu2O8+y. Phys Rev Lett 2011; 106:057003. [PMID: 21405423 DOI: 10.1103/physrevlett.106.057003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 12/23/2010] [Indexed: 05/30/2023]
Abstract
Competition with magnetism is at the heart of high-temperature superconductivity, most intensely felt near a vortex core. To investigate vortex magnetism we have developed a spatially resolved probe based upon NMR spin-lattice-relaxation spectroscopy. With this approach we have found a spin-density wave associated with the vortex core in Bi(2)Sr(2)CaCu(2)O(8+y), similar to checkerboard patterns in the local density of electronic states reported from scanning tunneling microscope experiments. We have determined both the spin-modulation amplitude and decay length from the vortex core in fields up to H=30 T.
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Affiliation(s)
- A M Mounce
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
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11
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Urbano RR, Green EL, Moulton WG, Reyes AP, Kuhns PL, Bittar EM, Adriano C, Garitezi TM, Bufaiçal L, Pagliuso PG. Distinct high-T transitions in underdoped Ba(1-x)KxFe2As2. Phys Rev Lett 2010; 105:107001. [PMID: 20867539 DOI: 10.1103/physrevlett.105.107001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Indexed: 05/29/2023]
Abstract
In contrast with the simultaneous structural and magnetic first order phase transition T0 previously reported, our detailed investigation on an underdoped Ba(0.84)K(0.16)Fe2As2 single crystal unambiguously revealed that the transitions are not concomitant. The tetragonal (τ: I4/mmm)-orthorhombic (ϑ: Fmmm) structural transition occurs at T(S)≃110 K, followed by an adjacent long-range antiferromagnetic (AFM) transition at T(N)≃102 K. Hysteresis and coexistence of the τ and ϑ phases over a finite temperature range observed by NMR experiments confirm the first order character of the τ-ϑ transition and provide evidence that both T(S) and T(N) are strongly correlated. Our data also show that superconductivity develops in the ϑ phase below T(c)=20 K and coexists with AFM. This new observation, T(S)≠T(N), firmly establishes another similarity between the hole-doped BaFe2As2 and the electron-doped iron-arsenide superconductors.
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Affiliation(s)
- R R Urbano
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
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12
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Lumata LL, Choi KY, Brooks JS, Reyes AP, Kuhns PL, Wu G, Chen XH. 77Se and 63Cu NMR studies of the electronic correlations in CuxTiSe2 (x = 0.05, 0.07). J Phys Condens Matter 2010; 22:295601. [PMID: 21399313 DOI: 10.1088/0953-8984/22/29/295601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a (77)Se and (63)Cu nuclear magnetic resonance (NMR) investigation on the charge-density-wave (CDW) superconductor Cu(x)TiSe(2) (x = 0.05 and 0.07). At high magnetic fields where superconductivity is suppressed, the temperature dependence of (77)Se and (63)Cu spin-lattice relaxation rates 1/T(1) follow a linear relation. The slope of (77)Se 1/T(1) versus T increases with the Cu doping. This can be described by a modified Korringa relation which suggests the significance of electronic correlations and the Se 4p- and Ti 3d-band contribution to the density of states at the Fermi level in the studied compounds.
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Affiliation(s)
- L L Lumata
- Department of Physics, Florida State University, Tallahassee, FL 32310, USA.
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13
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Zhou HD, Wiebe CR, Jo YJ, Balicas L, Urbano RR, Lumata LL, Brooks JS, Kuhns PL, Reyes AP, Qiu Y, Copley JRD, Gardner JS. Chemical pressure induced spin freezing phase transition in kagome pr langasites. Phys Rev Lett 2009; 102:067203. [PMID: 19257628 DOI: 10.1103/physrevlett.102.067203] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 12/12/2008] [Indexed: 05/27/2023]
Abstract
The 2D kagome system Pr3Ga5SiO14 has been previously identified as a spin-liquid candidate in zero field, displaying no magnetic long-ranged order down to at least 35 mK. Perturbations upon such systems, either under applied fields or applied pressure, should induce a spin freezing phase transition, but there are very few experimental realizations of this phenomena other than the well-studied 3D pyrochlore Tb2Ti2O7. In this Letter, we report the observation of a spin freezing phase transition in Pr3Ga5SiO14 through the application of chemical pressure--that is, through a systematic substitution on the Si site with larger ions and an elongation of the nearest-neighbor Pr-Pr distance in the kagome lattice. This results in a suppression of the T2 component of the heat capacity, and the reduction of the exchange constant eventually leads to dipolar-driven spin freezing.
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Affiliation(s)
- H D Zhou
- Department of Physics, Florida State University, Tallahassee, Florida 32306-3016, USA
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14
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Leighton C, Manno M, Cady A, Freeland JW, Wang L, Umemoto K, Wentzcovitch RM, Chen TY, Chien CL, Kuhns PL, Hoch MJR, Reyes AP, Moulton WG, Dahlberg ED, Checkelsky J, Eckert J. Composition controlled spin polarization in Co(1-x)Fe(x)S(2) alloys. J Phys Condens Matter 2007; 19:315219. [PMID: 21694119 DOI: 10.1088/0953-8984/19/31/315219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The transition metal (TM) chalcogenides of the form TMX(2) (X = S or Se) have been studied for decades due to their interesting electronic and magnetic properties such as metamagnetism and metal-insulator transitions. In particular, the Co(1-x)Fe(x)S(2) alloys were the subject of investigation in the 1970s due to general interest in itinerant ferromagnetism. In recent years (2000-present) it has been shown, both by electronic structure calculations and detailed experimental investigations, that Co(1-x)Fe(x)S(2) is a model system for the investigation of highly spin polarized ferromagnetism. The radically different electronic properties of the two endpoint compounds (CoS(2) is a narrow bandwidth ferromagnetic metal, while FeS(2) is a diamagnetic semiconductor), in a system forming a substitutional solid solution allows for composition control of the Fermi level relative to the spin split bands, and therefore composition-controlled conduction electron spin polarization. In essence, the recent work has shown that the concept of 'band engineering' can be applied to half-metallic ferromagnets and that high spin polarization can be deliberately engineered. Experiments reveal tunability in both sign and magnitude of the spin polarization at the Fermi level, with maximum values obtained to date of 85% at low temperatures. In this paper we review the properties of Co(1-x)Fe(x)S(2) alloys, with an emphasis on properties of relevance to half-metallicity. Crystal structure, electronic structure, synthesis, magnetic properties, transport properties, direct probes of the spin polarization, and measurements of the total density of states at the Fermi level are all discussed. We conclude with a discussion of the factors that influence, or even limit, the spin polarization, along with a discussion of opportunities and problems for future investigation, particularly with regard to fundamental studies of spintronic devices.
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Affiliation(s)
- C Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, USA
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15
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Kuhns PL, Hoch MJR, Reyes AP, Moulton WG, Wang L, Leighton C. Evolution with composition of the d-band density of states at the Fermi level in highly spin polarized Co1-xFexS2. Phys Rev Lett 2006; 96:167208. [PMID: 16712272 DOI: 10.1103/physrevlett.96.167208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 01/30/2006] [Indexed: 05/09/2023]
Abstract
Highly spin polarized (SP) and half-metallic ferromagnetic systems are of considerable current interest and of potential importance for spintronic applications. Recent work has demonstrated that Co1-xFexS2 is a highly polarized ferromagnet (FM) where the spin polarization can be tuned by alloy composition. Using 59Co FM-NMR as a probe, we have measured the low-temperature spin relaxation in this system in magnetic fields from 0 to 1.0 T for 0<or=x<or=0.3. The 59Co spin-lattice relaxation rates follow a linear T dependence. Analysis of the data, using expressions for a FM system, permits information to be obtained on the d-band density of states at the Fermi level. The results are compared with independent density of states values inferred from electronic specific heat measurements and band structure calculations. It is shown that FM-NMR can be an important method for investigating highly SP systems.
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Affiliation(s)
- P L Kuhns
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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16
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Gervais G, Stormer HL, Tsui DC, Kuhns PL, Moulton WG, Reyes AP, Pfeiffer LN, Baldwin KW, West KW. Evidence for skyrmion crystallization from NMR relaxation experiments. Phys Rev Lett 2005; 94:196803. [PMID: 16090197 DOI: 10.1103/physrevlett.94.196803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2004] [Indexed: 05/03/2023]
Abstract
A resistively detected NMR technique was used to probe the two-dimensional electron gas in a GaAs/AlGaAs quantum well. The spin-lattice relaxation rate (1/T(1)) was extracted at near complete filling of the first Landau level by electrons. The nuclear spin of (75)As is found to relax much more efficiently with T --> 0 and when a well developed quantum Hall state with R(xx) approximately 0 occurs. The data show a remarkable correlation between the nuclear spin relaxation and localization. This suggests that the magnetic ground state near complete filling of the first Landau level may contain a lattice of topological spin texture, i.e., a Skyrmion crystal.
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Affiliation(s)
- G Gervais
- Department of Physics, Columbia University, New York, New York 10027 USA
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17
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Zheng GQ, Kuhns PL, Reyes AP, Liang B, Lin CT. Critical point and the nature of the pseudogap of single-layered copper-oxide Bi2Sr2-xLaxCuO6+delta superconductors. Phys Rev Lett 2005; 94:047006. [PMID: 15783588 DOI: 10.1103/physrevlett.94.047006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Indexed: 05/24/2023]
Abstract
We apply strong magnetic fields of H=28.5 to 43 T to suppress superconductivity (SC) in the cuprates Bi2Sr2-xLaxCuO6+delta (x=0.65, 0.40, 0.25, 0.15, and 0), and investigate the low temperature (T) normal state by 63Cu nuclear spin-lattice relaxation rate (1/T1) measurements. We find that the pseudogap (PG) phase persists deep inside the overdoped region but terminates at x approximately 0.05, which corresponds to the hole doping concentration of approximately 0.21. Beyond this critical point, the normal state is a Fermi liquid that persists as the ground state when superconductivity is removed by the magnetic field. A comparison of the superconducting state with the H-induced normal state in the x=0.40 (Tc=32 K) sample indicates that there remains substantial part of the Fermi surface even in the fully developed PG state, which suggests that the PG and SC are coexisting matters.
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Affiliation(s)
- Guo-Qing Zheng
- Department of Physics, Okayama University, Okayama 700-8530, Japan
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18
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Kuhns PL, Hoch MJR, Moulton WG, Reyes AP, Wu J, Leighton C. Magnetic phase separation in La1-xSrxCoO3 by 59Co nuclear magnetic resonance. Phys Rev Lett 2003; 91:127202. [PMID: 14525396 DOI: 10.1103/physrevlett.91.127202] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Indexed: 05/24/2023]
Abstract
59Co NMR measurements on La1-xSrxCoO3 reported here establish unequivocally, for the first time, the coexistence of ferromagnetic regions, spin-glass regions, and hole-poor low spin regions at all x values from 0.1 to 0.5. A zero external field NMR spectrum, which is assigned to the ferromagnetic regions, has a spectral shape that is nearly x independent at 1.9 K, as are the relaxation times, T1 and T2. The integrated spectral area increases rapidly with x up to x = 0.2 and then decreases slightly for larger x. In a field of 9.97 T, a narrow NMR line is observed at 102 MHz, identical to that found in x = 0 samples in previous work. The integrated intensity of this spectrum decreases rapidly with increasing x, and is ascribed to hole-poor low spin regions. Beneath this spectrum, a third broad line, with a peak at 100 MHz, is assigned to a spin- or cluster-glass-like phase.
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Affiliation(s)
- P L Kuhns
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
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19
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Zheng GQ, Ozaki H, Kitaoka Y, Kuhns P, Reyes AP, Moulton WG. Delocalized quasiparticles in the vortex state of an overdoped high-T(c) superconductor probed by 63Cu NMR. Phys Rev Lett 2002; 88:077003. [PMID: 11863931 DOI: 10.1103/physrevlett.88.077003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2001] [Indexed: 05/23/2023]
Abstract
We report the spin Knight shift (K(s)) and the nuclear spin-lattice relaxation rate (1/T1) in the vortex state as a function of magnetic field (H) up to 28 T in the high-Tc superconductor TlSr2CaCu2O6.8 (Tc = 68 K). At low temperatures well below Tc, both K(s) and 1/T1 measured around the middle point between the two nearest vortices (saddle point) increase substantially with increasing field, which indicate that the quasiparticle states with an ungapped spectrum are extended outside the vortex cores in a d-wave superconductor. The density of states (DOS) around the saddle point is found to be kappaN(0)square root[H/H(c2)], with kappa = 0.5-0.7 and N0 being the normal-state DOS.
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Affiliation(s)
- G-q Zheng
- Department of Physical Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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20
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Bryant PL, Harwell CR, Mrse AA, Emery EF, Gan Z, Caldwell T, Reyes AP, Kuhns P, Hoyt DW, Simeral LS, Hall RW, Butler LG. Structural characterization of MAO and related aluminum complexes. 1. Solid-state (27)Al NMR with comparison to EFG tensors from ab initio molecular orbital calculations. J Am Chem Soc 2001; 123:12009-17. [PMID: 11724609 DOI: 10.1021/ja011092a] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experimental and ab initio molecular orbital techniques are developed for study of aluminum species with large quadrupole coupling constants to test structural models for methylaluminoxanes (MAO). The techniques are applied to nitrogen- and oxygen-containing complexes of aluminum and to solid MAO isolated from active commercial MAO preparations. (Aminato)- and (propanolato)aluminum clusters with 3-, 4-, and 6-coordinate aluminum sites are studied with three (27)Al NMR techniques optimized for large (27)Al quadrupole coupling constants: field-swept, frequency-stepped, and high-field MAS NMR. Four-membered (aminato)aluminum complexes with AlN(4) coordination yield slightly smaller C(q) values than similar AlN(2)C(2) sites: 12.2 vs 15.8 MHz. Planar 3-coordinate AlN(2)C sites have the largest C(q) values, 37 MHz. In all cases, molecular orbital calculations of the electric field gradient tensors yields C(q) and eta values that match with experiment, even for a large hexameric (aminato)aluminum cage. A D(3d) symmetry hexaaluminum oxane cluster, postulated as a model for MAO, yields a calculated C(q) of -23.7 MHz, eta = 0.7474, and predicts a spectrum that is too broad to match the field-swept NMR of methylaluminoxane, which shows at least three sites, all with C(q) values greater than 15 MHz but less than 21 MHz. Thus, the proposed hexaaluminum cluster, with its strained four-membered rings, is not a major component of MAO. However, calculations for dimers of the cage complex, either edge-bridged or face-bridged, show a much closer match to experiment. Also, MAO preparations differ, with a gel form of MAO having significantly larger (27)Al C(q) values than a nongel form, a conclusion reached on the basis of (27)Al NMR line widths in field-swept NMR spectra acquired from 13 to 24 T.
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Affiliation(s)
- P L Bryant
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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21
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Mitrović VF, Sigmund EE, Eschrig M, Bachman HN, Halperin WP, Reyes AP, Kuhns P, Moulton WG. Spatially resolved electronic structure inside and outside the vortex cores of a high-temperature superconductor. Nature 2001; 413:501-4. [PMID: 11586354 DOI: 10.1038/35097039] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Puzzling aspects of high-transition-temperature (high-Tc) superconductors include the prevalence of magnetism in the normal state and the persistence of superconductivity in high magnetic fields. Superconductivity and magnetism generally are thought to be incompatible, based on what is known about conventional superconductors. Recent results, however, indicate that antiferromagnetism can appear in the superconducting state of a high-Tc superconductor in the presence of an applied magnetic field. Magnetic fields penetrate a superconductor in the form of quantized flux lines, each of which represents a vortex of supercurrents. Superconductivity is suppressed in the core of the vortex and it has been suggested that antiferromagnetism might develop there. Here we report the results of a high-field nuclear-magnetic-resonance (NMR) imaging experiment in which we spatially resolve the electronic structure of near-optimally doped YBa2Cu3O7-delta inside and outside vortex cores. Outside the cores, we find strong antiferromagnetic fluctuations, whereas inside we detect electronic states that are rather different from those found in conventional superconductors.
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Affiliation(s)
- V F Mitrović
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
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22
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Hilleman DE, Reyes AP, Wurdeman RL, Faulkner M. Efficacy and safety of a therapeutic interchange from high-dose calcium channel blockers to a fixed-dose combination of amlodipine/benazepril in patients with moderate-to-severe hypertension. J Hum Hypertens 2001; 15:559-65. [PMID: 11494095 DOI: 10.1038/sj.jhh.1001230] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2000] [Revised: 02/22/2001] [Accepted: 03/16/2001] [Indexed: 11/08/2022]
Abstract
BACKGROUND Recent hypertension trials have demonstrated the importance of achieving goal blood pressures to reduce the risk of target organ damage. In patients with moderate to severe hypertension, the use of high-dose monotherapy and/or combinations of drugs are necessary to achieve these goals. Fixed-dose combination products may be useful in these patients by reducing the number of daily doses required to control blood pressure. OBJECTIVE The objective of the present study was to evaluate the efficacy and safety of a therapeutic interchange between high-dose calcium channel blocker therapy and a fixed-dose combination of amlodipine/ benazepril (Lotrel; Novartis Pharmaceuticals, USA) in patients with moderate to severe hypertension. METHODS A total of 75 patients were switched from amlodipine (n = 25), felodipine (n = 25), and nifedipine-GITS (n = 25) to amlodipine/benazepril. Twenty-eight of the 75 patients (37%) were taking either a beta-blocker or a diuretic in addition to the high-dose calcium channel blocker prior to the switch. Blood pressure control, side effects and the cost of the therapeutic interchange were evaluated in the year following the therapeutic interchange. RESULTS Sixty-six of the 75 (88%) patients were successfully switched with maintenance of blood pressure control and without the development of new dose-limiting side effects. Reasons for treatment failure after the therapeutic interchange included loss of blood pressure control in five patients and the development of new dose-limiting side effects in four patients. These side effects included cough in three patients and rash in one patient. After accounting for differences in drug acquisition cost and costs related to the switch (clinic and emergency room and laboratory tests), a cost savings of $16030 for all 75 patients was realised in the first year. The per patient-per year cost savings was $214. CONCLUSIONS Our data indicate that a therapeutic interchange from selected high-dose calcium channel blockers to a fixed-dose combination of amlodipine/ benazepril can be successfully accomplished in the majority of patients.
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Affiliation(s)
- D E Hilleman
- Creighton University School of Pharmacy and Allied Health Professions, 2500 California Plaza, Omaha, NE 68178, USA
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23
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Sigmund EE, Calder ES, Thomas GW, Mitrović VF, Bachman HN, Halperin WP, Kuhns PL, Reyes AP. NMR phase noise in bitter magnets. J Magn Reson 2001; 148:309-13. [PMID: 11237636 DOI: 10.1006/jmre.2000.2246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We have studied the temporal instability of a high field resistive Bitter magnet through nuclear magnetic resonance (NMR). This instability leads to transverse spin decoherence in repeated and accumulated NMR experiments as is normally performed during signal averaging. We demonstrate this effect via Hahn echo and Carr--Purcell--Meiboom--Gill (CPMG) transverse relaxation experiments in a 23-T resistive magnet. Quantitative analysis was found to be consistent with separate measurements of the magnetic field frequency fluctuation spectrum, as well as with independent NMR experiments performed in a magnetic field with a controlled instability. Finally, the CPMG sequence with short pulse delays is shown to be successful in recovering the intrinsic spin--spin relaxation even in the presence of magnetic field temporal instability.
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Affiliation(s)
- E E Sigmund
- Department of Physics, Northwestern University, Evanston, Illinois 60208, USA
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24
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Zheng G, Ozaki H, Clark WG, Kitaoka Y, Kuhns P, Reyes AP, Moulton WG, Kondo T, Shimakawa Y, Kubo Y. Superconducting fluctuations and the pseudogap in the slightly overdoped high- T(c) superconductor TlSr2CaCu2O6.8: high magnetic field NMR studies. Phys Rev Lett 2000; 85:405-408. [PMID: 10991294 DOI: 10.1103/physrevlett.85.405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2000] [Indexed: 05/23/2023]
Abstract
From measurements of the 63Cu Knight shift ( K) and the nuclear spin-lattice relaxation rate ( 1/T1) under magnetic fields from zero up to 28 T in the slightly overdoped high- T(c) superconductor TlSr2CaCu2O6.8 ( T(c) = 68 K), we find that the pseudogap behavior, i.e., the reductions of 1/T1T and K above T(c) from the values expected from the normal state at high T, is strongly field dependent and follows a scaling relation. We show that this scaling is consistent with the effects of the Cooper pair density fluctuations. The present finding contrasts sharply with the pseudogap property reported previously in the underdoped regime where no field effect was seen up to 23.2 T. The implications are discussed.
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Affiliation(s)
- Gq Zheng
- Department of Physical Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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25
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Mooss AN, Wurdeman RL, Mohiuddin SM, Reyes AP, Sugimoto JT, Scott W, Hilleman DE, Seyedroudbari A. Esmolol versus diltiazem in the treatment of postoperative atrial fibrillation/atrial flutter after open heart surgery. Am Heart J 2000; 140:176-80. [PMID: 10874282 DOI: 10.1067/mhj.2000.106917] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Supraventricular tachyarrhythmias are common after open heart surgery. Possible causative factors for these arrhythmias include operative trauma, atrial ischemia, electrolyte imbalances, pericardial irritation, and excess catecholamines. Two agents commonly used to control ventricular rate in atrial fibrillation or atrial flutter (AF/AFL) are beta-blockers and calcium channel blockers. METHODS AND RESULTS This randomized study was designed to compare the safety and efficacy of intravenous diltiazem versus intravenous esmolol in patients with postoperative AF/AFL after coronary bypass surgery and/or valve replacement surgery. A comparative cost analysis was also performed. Thirty patients received either esmolol (n = 15) or diltiazem (n = 15) for AF/AFL. During the first 6 hours of treatment, 66.6% of esmolol-treated patients converted to sinus rhythm compared with 13.3% of the diltiazem-treated patients (P <.05). At 24 hours, 66.6% of the diltiazem group converted to SR compared with 80% of the esmolol group (not significant). Drug-induced side effects, time to rate control (<90 beats/min), number of patients requiring cardioversion, and length of hospitalization were similar for the two groups. The drug cost/successfully treated patient for esmolol versus diltiazem was $254 versus $437 at 6 hours and $529 versus $262 at 24 hours. CONCLUSIONS Although this is a small study, it suggests that esmolol is more effective in converting patients to normal sinus rhythm than diltiazem during the initial dosing period. No differences in conversion rates were observed between the two groups after 24 hours. Additional studies are needed to confirm whether esmolol is the initial drug of choice in patients with postoperative AF/AFL after coronary bypass surgery.
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Affiliation(s)
- A N Mooss
- Creighton University Medical Center, Omaha, NE, USA
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26
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Bryant PL, Butler LG, Reyes AP, Kuhns P. 27Al field-swept and frequency-stepped NMR for sites with large quadrupole coupling constants. Solid State Nucl Magn Reson 2000; 16:63-67. [PMID: 10811430 DOI: 10.1016/s0926-2040(00)00055-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Spectra of nonspinning samples with large quadrupole coupling constants, 16-32 MHz, are acquired by frequency-stepping. A series of spin-echoes are acquired at arbitrary frequency increments, frequency-shifted in the time domain, and co-added as magnitude spectra. This procedure is derived from a method in use for field-swept NMR. The two methods are compared.
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Affiliation(s)
- P L Bryant
- Department of Chemistry, Louisiana State University, Baton Rouge 70803-1804, USA
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27
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Reyes AP, Heffner RH, Canfield PC, Thompson JD, Fisk Z. 209Bi NMR and NQR investigation of the small-gap semiconductor Ce3Bi4Pt3. Phys Rev B Condens Matter 1994; 49:16321-16330. [PMID: 10010781 DOI: 10.1103/physrevb.49.16321] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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28
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MacLaughlin DE, Vithayathil JP, Brom HB, Hammel PC, Canfield PC, Reyes AP, Fisk Z, Thompson JD, Cheong SW. Abrupt but continuous antiferromagnetic transition in nearly stoichiometric La2CuO4+ delta. Phys Rev Lett 1994; 72:760-763. [PMID: 10056516 DOI: 10.1103/physrevlett.72.760] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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29
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Ahrens ET, Hammel PC, Heffner RH, Reyes AP, Smith JL, Clark WG. NMR determination of the B substitutional site in UBe13-xBx. Phys Rev B Condens Matter 1993; 48:6691-6694. [PMID: 10009234 DOI: 10.1103/physrevb.48.6691] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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30
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Hammel PC, Reyes AP, Cheong SW, Fisk Z, Schirber JE. NMR study of local structure in metallic La2CuO4+ delta. Phys Rev Lett 1993; 71:440-443. [PMID: 10055271 DOI: 10.1103/physrevlett.71.440] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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31
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MacLaughlin DE, Hammel PC, Vithayathil JP, Canfield PC, Fisk Z, Heffner RH, Reyes AP, Thompson JD, Cheong S. Comment on "Order-disorder structural phase transition in La2-xSrxCu4+ delta at 150 K". Phys Rev Lett 1991; 67:525. [PMID: 10044917 DOI: 10.1103/physrevlett.67.525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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32
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Reyes AP, MacLaughlin DE, Takigawa M, Hammel PC, Heffner RH, Thompson JD, Crow JE. 63Cu NMR and hole depletion in the normal state of yttrium-rich Y1-xPrxBa2Cu3O7. Phys Rev B Condens Matter 1991; 43:2989-3001. [PMID: 9997601 DOI: 10.1103/physrevb.43.2989] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Takigawa M, Reyes AP, Hammel PC, Thompson JD, Heffner RH, Fisk Z, Ott KC. Cu and O NMR studies of the magnetic properties of YBa2Cu3O6.63 (Tc=62 K). Phys Rev B Condens Matter 1991; 43:247-257. [PMID: 9996209 DOI: 10.1103/physrevb.43.247] [Citation(s) in RCA: 328] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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34
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Hammel PC, Reyes AP, Fisk Z, Takigawa M, Thompson JD, Heffner RH, Cheong SW, Schirber JE. 139La NMR study of phase separation in single-crystal La2CuO4+ delta. Phys Rev B Condens Matter 1990; 42:6781-6783. [PMID: 9994784 DOI: 10.1103/physrevb.42.6781] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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35
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Reyes AP, MacLaughlin DE, Takigawa M, Hammel PC, Heffner RH, Thompson JD, Crow JE, Kebede A, Mihalisin T, Schwegler J. Observation of Cu NMR in antiferromagnetic PrBa2Cu3O7: Evidence for hole-band filling. Phys Rev B Condens Matter 1990; 42:2688-2691. [PMID: 9995751 DOI: 10.1103/physrevb.42.2688] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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