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Willenberg B, Schäpers M, Wolter AUB, Drechsler SL, Reehuis M, Hoffmann JU, Büchner B, Studer AJ, Rule KC, Ouladdiaf B, Süllow S, Nishimoto S. Complex Field-Induced States in Linarite PbCuSO4(OH)2 with a Variety of High-Order Exotic Spin-Density Wave States. Phys Rev Lett 2016; 116:047202. [PMID: 26871354 DOI: 10.1103/physrevlett.116.047202] [Citation(s) in RCA: 5] [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: 08/13/2015] [Indexed: 06/05/2023]
Abstract
Low-temperature neutron diffraction and NMR studies of field-induced phases in linarite are presented for magnetic fields H∥b axis. A two-step spin-flop transition is observed, as well as a transition transforming a helical magnetic ground state into an unusual magnetic phase with sine-wave-modulated moments ∥H. An effective J[over ˜]_{1}-J[over ˜]_{2} single-chain model with a magnetization-dependent frustration ratio α_{eff}=-J[over ˜]_{2}/J[over ˜]_{1} is proposed. The latter is governed by skew interchain couplings and shifted to the vicinity of the ferromagnetic critical point. It explains qualitatively the observation of a rich variety of exotic longitudinal collinear spin-density wave, SDW_{p}, states (9≥p≥2).
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Affiliation(s)
- B Willenberg
- Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| | - M Schäpers
- Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany
| | - A U B Wolter
- Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany
| | - S-L Drechsler
- Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany
| | - M Reehuis
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| | - J-U Hoffmann
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| | - B Büchner
- Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany
- Institut für Festkörperphysik, TU Dresden, D-01062 Dresden, Germany
| | - A J Studer
- The Bragg Institute, ANSTO, Kirrawee DC, New South Wales 2234, Australia
| | - K C Rule
- The Bragg Institute, ANSTO, Kirrawee DC, New South Wales 2234, Australia
| | - B Ouladdiaf
- Institute Laue-Langevin, F-38042 Grenoble Cedex, France
| | - S Süllow
- Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany
| | - S Nishimoto
- Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany
- Institut für Festkörperphysik, TU Dresden, D-01062 Dresden, Germany
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Wang JL, Caron L, Campbell SJ, Kennedy SJ, Hofmann M, Cheng ZX, Din MFM, Studer AJ, Brück E, Dou SX. Driving magnetostructural transitions in layered intermetallic compounds. Phys Rev Lett 2013; 110:217211. [PMID: 23745927 DOI: 10.1103/physrevlett.110.217211] [Citation(s) in RCA: 6] [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: 11/12/2012] [Indexed: 06/02/2023]
Abstract
We report the dramatic effect of applied pressure and magnetic field on the layered intermetallic compound Pr(0.5)Y(0.5)Mn(2)Ge(2). In the absence of pressure or magnetic field this compound displays interplanar ferromagnetism at room temperature and undergoes an isostructural first order magnetic transition (FOMT) to an antiferromagnetic state below 158 K, followed by another FOMT at 50 K due to the reemergence of ferromagnetism as praseodymium orders (T(C)(Pr)). The application of a magnetic field drives these two transitions towards each other, whereas the application of pressure drives them apart. Pressure also produces a giant magnetocaloric effect such that a threefold increase of the entropy change associated with the lower FOMT (at T(C)(Pr)) is seen under a pressure of 7.5 kbar. First principles calculations, using density functional theory, show that this remarkable magnetic behavior derives from the strong magnetoelastic coupling of the manganese layers in this compound.
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Affiliation(s)
- J L Wang
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia.
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Hudspeth JM, Goossens DJ, Gutmann MJ, Studer AJ. A neutron diffraction study of the phase transition of fully deuterated triglycine sulphate (ND2CD2COOD)3.D2SO4. Cryst Res Technol 2013. [DOI: 10.1002/crat.201300061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Shamba P, Wang JL, Debnath JC, Kennedy SJ, Zeng R, Din MFM, Hong F, Cheng ZX, Studer AJ, Dou SX. The magnetocaloric effect and critical behaviour of the Mn(0.94)Ti(0.06)CoGe alloy. J Phys Condens Matter 2013; 25:056001. [PMID: 23262456 DOI: 10.1088/0953-8984/25/5/056001] [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: 06/01/2023]
Abstract
Structural, magnetic and magnetocaloric properties of the Mn(0.94)Ti(0.06)CoGe alloy have been investigated using x-ray diffraction, DC magnetization and neutron diffraction measurements. Two phase transitions have been detected, at T(str) = 235 K and T(C) = 270 K. A giant magnetocaloric effect has been obtained at around T(str) associated with a structural phase transition from the low temperature orthorhombic TiNiSi-type structure to the high temperature hexagonal Ni(2)In-type structure, which is confirmed by neutron study. In the vicinity of the structural transition, at T(str), the magnetic entropy change, -ΔS(M) reached a maximum value of 14.8 J kg(-1) K(-1) under a magnetic field of 5 T, which is much higher than that previously reported for the parent compound MnCoGe. To investigate the nature of the magnetic phase transition around T(C) = 270 K from the ferromagnetic to the paramagnetic state, we performed a detailed critical exponent study. The critical components γ, β and δ determined using the Kouvel-Fisher method, the modified Arrott plot and the critical isotherm analysis agree well. The values deduced for the critical exponents are close to the theoretical prediction from the mean-field model, indicating that the magnetic interactions are long range. On the basis of these critical exponents, the magnetization, field and temperature data around T(C) collapse onto two curves obeying the single scaling equation M(H,ε) = ε(β)f ± (H/ε(β+γ)).
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Affiliation(s)
- P Shamba
- Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
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Hudspeth JM, Goossens DJ, Studer AJ, Withers RL, Norén L. The crystal and magnetic structures of LaCa(2)Fe(3)O(8) and NdCa(2)Fe(3)O(8). J Phys Condens Matter 2009; 21:124206. [PMID: 21817448 DOI: 10.1088/0953-8984/21/12/124206] [Citation(s) in RCA: 5] [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] [Indexed: 05/31/2023]
Abstract
The crystal and magnetic structures of LaCa(2)Fe(3)O(8) and NdCa(2)Fe(3)O(8) have been established using a combination of x-ray, neutron and electron diffraction. It was already considered likely that LaCa(2)Fe(3)O(8) and NdCa(2)Fe(3)O(8) were made up of stacked perovskite-like layers of FeO(6) octahedra, with every third layer being replaced by a layer of tetrahedrally coordinated Fe, rather like a variation on the Brownmillerite (Ca(2)Fe(2)O(5)) structure type. We have gone further and determined a likely space group for this Grenier phase and determined the magnetic structure of the compounds at room temperature. The space group is found to be P 2(1)ma (b axis as the long axis), and the crystal structure has been refined, subject to the stacking faulting along the long axis that is apparent in electron diffraction patterns. The magnetic structure of LaCa(2)Fe(3)O(8) is shown to consist of antiferromagnetically ordered Fe(3+) ions on a collinear G-type antiferromagnetic structure, with the magnetic moments most likely (anti)parallel with the c axis, and of magnitude 3.4 ± 0.2μ(B) (3.6 ± 0.2μ(B) for NdCa(2)Fe(3)O(8)). The result is reasonable given the magnetic structures of the end members of the La(1-x)Ca(x)FeO(3) series, LaFeO(3) (x = 0) and Ca(2)Fe(2)O(5) (x = 1).
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Affiliation(s)
- J M Hudspeth
- Department of Physics, The Australian National University, Canberra, ACT 0200, Australia
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Wang JL, Campbell SJ, Studer AJ, Avdeev M, Zeng R, Dou SX. Magnetic phase transitions in Pr(1-x)Lu(x)Mn(2)Ge(2) compounds. J Phys Condens Matter 2009; 21:124217. [PMID: 21817459 DOI: 10.1088/0953-8984/21/12/124217] [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: 05/31/2023]
Abstract
The effects of replacing Pr by Lu on the magnetic behaviour and structures of Pr(1-x)Lu(x)Mn(2)Ge(2) (x = 0.2,x = 0.4) have been investigated using x-ray diffraction, Mössbauer spectroscopy, magnetization and neutron diffraction measurements. The substitution of Lu for Pr leads to a decrease in the lattice constants a, c and the unit cell volume V at room temperature with this contraction of the unit cell resulting in modifications of the Pr(1-x)Lu(x)Mn(2)Ge(2) magnetic structures. Four and five magnetic phase transitions-linked primarily with temperature driven changes in the intralayer Mn-Mn separation distances-have been detected within the temperature range 4.5-550 K for Pr(0.8)Lu(0.2)Mn(2)Ge(2) and Pr(0.6)Lu(0.4)Mn(2)Ge(2), respectively, with re-entrant ferromagnetism being detected around T(C)(Pr)∼31 K for Pr(0.6)Lu(0.4)Mn(2)Ge(2). It was found that T(C)(inter) and T(C)(Pr) increase with increasing applied field while T(N)(inter) decreases for Pr(0.6)Lu(0.4)Mn(2)Ge(2), indicating that the canted antiferromagnetic AFmc region contracts with increasing field. The Debye temperatures for Pr(1-x)Lu(x)Mn(2)Ge(2) with x = 0.2 and 0.4 were evaluated as θ(D) = 320 ± 40 K and θ(D) = 400 ± 20 K respectively from the temperature dependence of the average isomer shift. The magnetic structures of both compounds have been determined by means of neutron diffraction measurements over the temperature range 3-300 K with formation of the Fmi magnetic state below T(c/c) = 192 K for Pr(0.8)Lu(0.2)Mn(2)Ge(2) and the occurrence of re-entrant ferromagnetism below T(C)(Pr) = 31 K for Pr(0.6)Lu(0.4)Mn(2)Ge(2) being confirmed.
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Affiliation(s)
- J L Wang
- School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, The Australian Defence Force Academy, Canberra ACT 2600, Australia. Bragg Institute, ANSTO, Lucas Heights, NSW 2234, Australia. Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
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Etschmann BE, Pring A, Putnis A, McCammon C, GrGuric B, Studer AJ. Kinetics of exsolution in the pentlandite-pyrrhotite ((Fe,Ni) 9S 8-Fe (1−x)S) system. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302090785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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Wang ZH, Swift PD, Studer AJ, McKenzie DR, James BW, Falconer IS. Light emission from a titanium vacuum arc using Fizeau interferometry with parallel detection. Appl Opt 1990; 29:5145-5150. [PMID: 20577526 DOI: 10.1364/ao.29.005145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The lineshape of light emission from a titanium vacuum arc was studied using a Fizeau interferometer coupled with an optical multichannel analyzer (OMA). A viewing geometry normal to the cathode surface was employed. Temperatures of ~3 x 10(5) K and ~3.5 x 10(4) K were obtained for titanium ions and titanium atoms present in the cathode spot, respectively. In light of results from previous work, a case is made for the latter temperature being the actual heavy species temperature in the cathode spot.
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