1
|
Abstract
CaFe2As2 exhibits collapsed tetragonal (cT) structure and varied exotic behaviour under pressure at low temperatures that led to debate on linking the structural changes to its exceptional electronic properties like superconductivity, magnetism, etc. Here, we investigate the electronic structure of CaFe2As2 forming in different structures employing density functional theory. The results indicate that the stability of the cT phase under pressure arises from the enhancement in hybridization induced effects and shift of the energy bands towards lower energies. The Fermi surface centered around Γ point gradually vanishes with the increase in pressure. Consequently, the nesting between the hole and electron Fermi surfaces associated to the spin density wave state disappears indicating a pathway to achieve the proximity to quantum fluctuations. The magnetic moment at the Fe sites diminishes in the cT phase consistent with the magnetic susceptibility results. Notably, the hybridization of Ca 4s states (Ca-layer may be treated as a charge reservoir layer akin to those in cuprate superconductors) is significantly enhanced in the cT phase revealing its relevance in its interesting electronic properties.
Collapse
Affiliation(s)
- Khadiza Ali
- Department of Condensed Matter Physics and Materials' Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, 400 005, India
| | - Kalobaran Maiti
- Department of Condensed Matter Physics and Materials' Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, 400 005, India.
| |
Collapse
|
2
|
Mou D, Kong T, Meier WR, Lochner F, Wang LL, Lin Q, Wu Y, Bud'ko SL, Eremin I, Johnson DD, Canfield PC, Kaminski A. Enhancement of the Superconducting Gap by Nesting in CaKFe_{4}As_{4}: A New High Temperature Superconductor. PHYSICAL REVIEW LETTERS 2016; 117:277001. [PMID: 28084772 DOI: 10.1103/physrevlett.117.277001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Indexed: 06/06/2023]
Abstract
We use high resolution angle resolved photoemission spectroscopy and density functional theory with measured crystal structure parameters to study the electronic properties of CaKFe_{4}As_{4}. In contrast to the related CaFe_{2}As_{2} compounds, CaKFe_{4}As_{4} has a high T_{c} of 35 K at stochiometric composition. This presents a unique opportunity to study the properties of high temperature superconductivity in the iron arsenides in the absence of doping or substitution. The Fermi surface consists of several hole and electron pockets that have a range of diameters. We find that the values of the superconducting gap are nearly isotropic (within the explored portions of the Brillouin zone), but are significantly different for each of the Fermi surface (FS) sheets. Most importantly, we find that the momentum dependence of the gap magnitude plotted across the entire Brillouin zone displays a strong deviation from the simple cos(k_{x})cos(k_{y}) functional form of the gap function, proposed by the scenario of Cooper pairing driven by a short range antiferromagnetic exchange interaction. Instead, the maximum value of the gap is observed on FS sheets that are closest to the ideal nesting condition, in contrast to previous observations in other ferropnictides. These results provide strong support for the multiband character of superconductivity in CaKFe_{4}As_{4}, in which Cooper pairing forms on the electron and the hole bands interacting via a dominant interband repulsive interaction, enhanced by band nesting.
Collapse
Affiliation(s)
- Daixiang Mou
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Tai Kong
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - William R Meier
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Felix Lochner
- Institut fur Theoretische Physik III, Ruhr-Universitat Bochum, 44801 Bochum, Germany
| | - Lin-Lin Wang
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Qisheng Lin
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
| | - Yun Wu
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - S L Bud'ko
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Ilya Eremin
- Institut fur Theoretische Physik III, Ruhr-Universitat Bochum, 44801 Bochum, Germany
| | - D D Johnson
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
- Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA
| | - P C Canfield
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Adam Kaminski
- Division of Materials Science and Engineering, Ames Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| |
Collapse
|
3
|
Mannella N. The magnetic moment enigma in Fe-based high temperature superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:473202. [PMID: 25352180 DOI: 10.1088/0953-8984/26/47/473202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The determination of the most appropriate starting point for the theoretical description of Fe-based materials hosting high-temperature superconductivity remains among the most important unsolved problem in this relatively new field. Most of the work to date has focused on the pnictides, with LaFeAsO, BaFe(2)As(2) and LiFeAs being representative parent compounds of three families known as 1111, 122 and 111, respectively. This topical review examines recent progress in this area, with particular emphasis on the implication of experimental data which have provided evidence for the presence of electron itinerancy and the detection of local spin moments. In light of the results presented, the necessity of a theoretical framework contemplating the presence and the interplay between itinerant electrons and large spin moments is discussed. It is argued that the physics at the heart of the macroscopic properties of pnictides Fe-based high-temperature superconductors appears to be far more complex and interesting than initially predicted.
Collapse
Affiliation(s)
- Norman Mannella
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN,USA
| |
Collapse
|
4
|
Gofryk K, Saparov B, Durakiewicz T, Chikina A, Danzenbächer S, Vyalikh DV, Graf MJ, Sefat AS. Fermi-surface reconstruction and complex phase equilibria in CaFe2As2. PHYSICAL REVIEW LETTERS 2014; 112:186401. [PMID: 24856707 DOI: 10.1103/physrevlett.112.186401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Indexed: 06/03/2023]
Abstract
Fermi-surface topology governs the relationship between magnetism and superconductivity in iron-based materials. Using low-temperature transport, angle-resolved photoemission, and x-ray diffraction, we show unambiguous evidence of large Fermi-surface reconstruction in CaFe2As2 at magnetic spin-density-wave and nonmagnetic collapsed-tetragonal (cT) transitions. For the cT transition, the change in the Fermi-surface topology has a different character with no contribution from the hole part of the Fermi surface. In addition, the results suggest that the pressure effect in CaFe2As2 is mainly leading to a rigid-band-like change of the valence electronic structure. We discuss these results and their implications for magnetism and superconductivity in this material.
Collapse
Affiliation(s)
- K Gofryk
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - B Saparov
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Durakiewicz
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A Chikina
- Department of Physics, St. Petersburg State University, St. Petersburg 198504, Russia and Institute of Solid State Physics, Dresden University of Technology, Zellescher Weg 16, D-01062 Dresden, Germany
| | - S Danzenbächer
- Institute of Solid State Physics, Dresden University of Technology, Zellescher Weg 16, D-01062 Dresden, Germany
| | - D V Vyalikh
- Department of Physics, St. Petersburg State University, St. Petersburg 198504, Russia and Institute of Solid State Physics, Dresden University of Technology, Zellescher Weg 16, D-01062 Dresden, Germany
| | - M J Graf
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A S Sefat
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
5
|
Kim YK, Jung WS, Han GR, Choi KY, Chen CC, Devereaux TP, Chainani A, Miyawaki J, Takata Y, Tanaka Y, Oura M, Shin S, Singh AP, Lee HG, Kim JY, Kim C. Existence of orbital order and its fluctuation in superconducting Ba(Fe(1-x)Co(x))2As2 single crystals revealed by x-ray absorption spectroscopy. PHYSICAL REVIEW LETTERS 2013; 111:217001. [PMID: 24313517 DOI: 10.1103/physrevlett.111.217001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Indexed: 06/02/2023]
Abstract
We performed temperature dependent x-ray linear dichroism (XLD) experiments on an iron pnictide system, Ba(Fe(1-x)Co(x))2As2 with x=0.00, 0.05, 0.08, and 0.10 to experimentally verify the existence of orbital ordering (OO). Substantial XLD was observed in polarization dependent x-ray absorption spectra of Fe L edges. By exploiting the difference in the temperature dependent behaviors, OO, and structure contributions to XLD could be clearly separated. The observed OO signal indicates different occupation numbers for d(yz) and d(zx) orbitals and supports the existence of ferro-OO. The results are also consistent with the theoretical prediction. Moreover, we find substantial OO signal well above the structural and magnetic transition temperatures, which suggests the existence of strong OO fluctuations up to high temperatures.
Collapse
Affiliation(s)
- Y K Kim
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Korea
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Adhikary G, Sahadev N, Biswas D, Bindu R, Kumar N, Thamizhavel A, Dhar SK, Maiti K. Electronic structure of EuFe2As2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:225701. [PMID: 23656758 DOI: 10.1088/0953-8984/25/22/225701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Employing high resolution photoemission spectroscopy, we studied the temperature evolution of the electronic structure of EuFe2As2, a unique pnictide, where antiferromagnetism of the Eu layer survives within the superconducting phase due to 'FeAs' layers, achieved via substitution and/or pressure. High energy and angle resolution helped to reveal the signature of peak-dip features, having significant p orbital character and spin density wave transition induced band folding in the electronic structure. A significant spectral weight redistribution is observed below 20 K manifesting the influence of antiferromagnetic order on the conduction electrons.
Collapse
Affiliation(s)
- Ganesh Adhikary
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005, India
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Ma C, Yang H, Tian H, Shi H, Wang Z, Li J. Contribution of interlayer hybridization to the electronic structure in iron pnictides: a study of EELS and first-principles calculations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:115503. [PMID: 23411508 DOI: 10.1088/0953-8984/25/11/115503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using electron energy loss spectroscopy (EELS) measurements and first-principles electronic structure calculations, the significant interlayer hybridization between the insulating layers (ReO or Ba) and the conducting FeAs layers was investigated in the layered iron pnictides, which is quite different from the case in the cuprate superconductors. This interlayer hybridization would result in an increase in the bandwidth near the Fermi level and interorbital charge transfer in the Fe 3d orbitals, which subsequently leads to a decrease in the Fe local moment and the modification of the Fermi surface topology. Therefore, a three-dimensional character of the electronic structure due to the interlayer hybridization is expected, as observed in previous experiments. These findings indicate that reduced dimensionality is no longer a necessary condition in the search for high-T(c) superconductors in iron pnictides.
Collapse
Affiliation(s)
- Chao Ma
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | | | | | | | | | | |
Collapse
|
8
|
Dhaka RS, Hahn SE, Razzoli E, Jiang R, Shi M, Harmon BN, Thaler A, Bud'ko SL, Canfield PC, Kaminski A. Unusual temperature dependence of band dispersion in Ba(Fe(1-x)Ru(x))2As2 and its consequences for antiferromagnetic ordering. PHYSICAL REVIEW LETTERS 2013; 110:067002. [PMID: 23432293 DOI: 10.1103/physrevlett.110.067002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Indexed: 06/01/2023]
Abstract
We have performed detailed studies of the temperature evolution of the electronic structure in Ba(Fe(1-x)Ru(x))(2)As(2) using angle resolved photoemission spectroscopy. Surprisingly, we find that the binding energy of both hole and electron bands changes significantly with temperature in both pure and Ru substituted samples. The hole and electron pockets are well nested at low temperature in unsubstituted (BaFe(2)As(2)) samples, which likely drives the spin density wave and resulting antiferromagnetic order. Upon warming, this nesting is degraded as the hole pocket shrinks and the electron pocket expands. Our results demonstrate that the temperature dependent nesting may play an important role in driving the antiferromagnetic-paramagnetic phase transition.
Collapse
Affiliation(s)
- R S Dhaka
- Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Dhaka RS, Liu C, Fernandes RM, Jiang R, Strehlow CP, Kondo T, Thaler A, Schmalian J, Bud'ko SL, Canfield PC, Kaminski A. What controls the phase diagram and superconductivity in Ru-substituted BaFe2As2? PHYSICAL REVIEW LETTERS 2011; 107:267002. [PMID: 22243178 DOI: 10.1103/physrevlett.107.267002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Indexed: 05/31/2023]
Abstract
We use high resolution angle-resolved photoemission to study the electronic structure of the iron based high-temperature superconductors Ba(Fe(1-x)Ru(x))(2)As(2) as a function of Ru concentration. We find that substitution of Ru for Fe is isoelectronic, i.e., it does not change the value of the chemical potential. More interestingly, there are no measured, significant changes in the shape of the Fermi surface or in the Fermi velocity over a wide range of substitution levels (0<x<0.55). Given that the suppression of the antiferromagnetic and structural phase is associated with the emergence of the superconducting state, Ru substitution must achieve this via a mechanism that does not involve changes of the Fermi surface. We speculate that this mechanism relies on magnetic dilution which leads to the reduction of the effective Stoner enhancement.
Collapse
Affiliation(s)
- R S Dhaka
- Division of Materials Science and Engineering, The Ames Laboratory, U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Terashima T, Kurita N, Tomita M, Kihou K, Lee CH, Tomioka Y, Ito T, Iyo A, Eisaki H, Liang T, Nakajima M, Ishida S, Uchida SI, Harima H, Uji S. Complete Fermi surface in BaFe2As2 observed via Shubnikov-de Haas oscillation measurements on detwinned single crystals. PHYSICAL REVIEW LETTERS 2011; 107:176402. [PMID: 22107545 DOI: 10.1103/physrevlett.107.176402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Indexed: 05/31/2023]
Abstract
We show that the Fermi surface (FS) in the antiferromagnetic phase of BaFe(2)As(2) is composed of one hole and two electron pockets, all of which are three dimensional and closed, in sharp contrast to the FS observed by angle-resolved photoemission spectroscopy. Considerations on the carrier compensation and Sommerfeld coefficient rule out existence of unobserved FS pockets of significant sizes. A standard band structure calculation reasonably accounts for the observed FS, despite the overestimated ordered moment. The mass enhancement, the ratio of the effective mass to the band mass, is 2-3.
Collapse
Affiliation(s)
- Taichi Terashima
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
van Heumen E, Vuorinen J, Koepernik K, Massee F, Huang Y, Shi M, Klei J, Goedkoop J, Lindroos M, van den Brink J, Golden MS. Existence, character, and origin of surface-related bands in the high temperature iron pnictide superconductor BaFe(2-x)Co(x)As2. PHYSICAL REVIEW LETTERS 2011; 106:027002. [PMID: 21405247 DOI: 10.1103/physrevlett.106.027002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Indexed: 05/30/2023]
Abstract
Low energy electron diffraction (LEED) experiments, LEED simulations, and finite slab density functional calculations are combined to study the cleavage surface of Co doped BaFe(2-x)Co(x)As2 (x = 0.1,0.17). We demonstrate that the energy dependence of the LEED data can only be understood from a terminating 1/2 Ba layer accompanied by distortions of the underlying As-Fe2-As block. As a result, surface-related Fe 3d states are present in the electronic structure, which we identify in angle resolved photoemission spectroscopy (ARPES) experiments. The close proximity of the surface-related states to the bulk bands inevitably leads to broadening of the ARPES signals, which excludes the use of the BaFe(2-x)Co(x)As2 system for accurate determination of self-energies using ARPES.
Collapse
Affiliation(s)
- Erik van Heumen
- van der Waals-Zeeman institute, University of Amsterdam, 1018 XL Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Analytis JG, Chu JH, McDonald RD, Riggs SC, Fisher IR. Enhanced Fermi-surface nesting in superconducting BaFe2(As(1-x)P(x))2 revealed by the de Haas-van Alphen effect. PHYSICAL REVIEW LETTERS 2010; 105:207004. [PMID: 21231258 DOI: 10.1103/physrevlett.105.207004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Indexed: 05/30/2023]
Abstract
The three-dimensional Fermi-surface morphology of superconducting BaFe2(As0.37P0.63)2 with T(c)=9 K is determined using the de Haas-van Alphen effect. The inner electron pocket has a similar area and k(z) interplane warping to the observed hole pocket, revealing that the Fermi surfaces are geometrically well nested in the (π,π) direction. These results are in stark contrast to the fermiology of the nonsuperconducting phosphides (x=1), and therefore suggest an important role for nesting in pnictide superconductivity.
Collapse
Affiliation(s)
- J G Analytis
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | | | | | | | | |
Collapse
|
13
|
Zhang Y, Yang LX, Chen F, Zhou B, Wang XF, Chen XH, Arita M, Shimada K, Namatame H, Taniguchi M, Hu JP, Xie BP, Feng DL. Out-of-plane momentum and symmetry-dependent energy gap of the pnictide Ba0.6K0.4Fe2As2 superconductor revealed by angle-resolved photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2010; 105:117003. [PMID: 20867600 DOI: 10.1103/physrevlett.105.117003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Indexed: 05/29/2023]
Abstract
The three-dimensional band structure and superconducting gap of Ba0.6K0.4Fe2As2 are studied with angle-resolved photoemission spectroscopy. In contrast with previous results, we have identified three holelike Fermi surface sheets near the zone center with sizable out-of-plane or kz dispersion. The superconducting gap on certain Fermi surface sheets shows significant kz dependence. Moreover, the superconducting gap sizes are different at the same Fermi momentum for two bands with different spatial symmetries (one odd, one even). Our results further reveal the three-dimensional and orbital-dependent structure of the superconducting gap in iron pnictides, which facilitates the understanding of momentum-integrated measurements and provides a distinct test for theories.
Collapse
Affiliation(s)
- Y Zhang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Richard P, Nakayama K, Sato T, Neupane M, Xu YM, Bowen JH, Chen GF, Luo JL, Wang NL, Dai X, Fang Z, Ding H, Takahashi T. Observation of Dirac cone electronic dispersion in BaFe2As2. PHYSICAL REVIEW LETTERS 2010; 104:137001. [PMID: 20481905 DOI: 10.1103/physrevlett.104.137001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 12/17/2009] [Indexed: 05/29/2023]
Abstract
We performed an angle-resolved photoemission spectroscopy study of BaFe2As2, which is the parent compound of the so-called 122 phase of the iron-pnictide high-temperature superconductors. We reveal the existence of a Dirac cone in the electronic structure of this material below the spin-density-wave temperature, which is responsible for small spots of high photoemission intensity at the Fermi level. Our analysis suggests that the cone is slightly anisotropic and its apex is located very near the Fermi level, leading to tiny Fermi surface pockets. The bands forming the cone show an anisotropic leading edge gap away from the cone that suggests a nodal spin-density-wave description.
Collapse
Affiliation(s)
- P Richard
- WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Harriger LW, Schneidewind A, Li S, Zhao J, Li Z, Lu W, Dong X, Zhou F, Zhao Z, Hu J, Dai P. Transition from three-dimensional anisotropic spin excitations to two-dimensional spin excitations by electron doping the FeAs-based BaFe1.96Ni0.04As2 superconductor. PHYSICAL REVIEW LETTERS 2009; 103:087005. [PMID: 19792752 DOI: 10.1103/physrevlett.103.087005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Indexed: 05/28/2023]
Abstract
We use neutron scattering to study the effect of electron doping on the structural or magnetic order in BaFe2As2. In the undoped state, BaFe2As2 exhibits simultaneous structural and magnetic phase transitions below 143 K. Upon electron doping to form BaFe1.96Ni0.04As2, the system first displays the lattice distortion near approximately 97 K, and then orders antiferromagnetically at 91 K before developing weak superconductivity below approximately 15 K. The effect of electron doping is to reduce the c-axis exchange coupling in BaFe2As2 and induce quasi-two-dimensional (2D) spin excitations. These results suggest that the transition from 3D spin waves to quasi-2D spin excitations by electron doping is important for the separated structural and magnetic phase transitions in iron arsenides.
Collapse
Affiliation(s)
- Leland W Harriger
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|