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Lane C, Piva MM, Rosa PFS, Zhu JX. Correlation versus hybridization gap in CaMn[Formula: see text]Bi[Formula: see text]. Sci Rep 2023; 13:9271. [PMID: 37286629 PMCID: PMC10247774 DOI: 10.1038/s41598-023-35812-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/24/2023] [Indexed: 06/09/2023] Open
Abstract
We study the interplay between electronic correlations and hybridization in the low-energy electronic structure of CaMn[Formula: see text]Bi[Formula: see text], a candidate hybridization-gap semiconductor. By employing a DFT+U approach we find both the antiferromagnetic Néel order and band gap in good agreement with the corresponding experimental values. Under hydrostatic pressure, we find a crossover from hybridization gap to charge-transfer insulting physics due to the delicate balance of hybridization and correlations. Increasing the pressure above [Formula: see text] GPa we find a simultaneous pressure-induced volume collapse, plane-to-chain, insulator to metal transition. Finally, we have also analyzed the topology in the antiferromagnetic CaMn[Formula: see text]Bi[Formula: see text] for all pressures studied.
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Affiliation(s)
- Christopher Lane
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
| | - M. M. Piva
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
- Institudo de Física “Gleb Wataghin”, UNICAMP, Campinas, SP 13083-859 Brazil
| | - P. F. S. Rosa
- Division of Materials Physics and Application, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
| | - Jian-Xin Zhu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
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2
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Christovam DS, Freitas GS, Piva MM, Souza JC, Malcolms MO, Canton OL, Leão JB, Ratcliff W, Lynn JW, Adriano C, Pagliuso PG. Evolution of the magnetic properties in the antiferromagnet Ce 2RhIn 8 simultaneously doped with Cd and Ir. Phys Rev B 2020; 102:10.1103/PhysRevB.102.195137. [PMID: 37720206 PMCID: PMC10502707 DOI: 10.1103/physrevb.102.195137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
We report the evolution of the magnetic properties of C e 2 R h 1 - x I r x I n 8 - y C d y single crystals. In particular, for C e 2 R h 0.5 I r 0.5 I n 8 (T N = 2.0 K ) and C e 2 R h 0.5 I r 0.5 I n 7.79 C d 0.21 (T N = 4.2 K ), we have solved the magnetic structure of these compounds using single-crystal neutron magnetic diffraction experiments. Taking the magnetic structure of the C e 2 R h I n 8 heavy-fermion antiferromagnet as a reference, we have identified no changes in the q = 1 2 , 1 2 , 0 magnetic wave vector; however, the direction of the ordered Ce3+ moments rotates toward the a b plane, under the influence of both dopants. By constraining the analysis of the crystalline electric field (CEF) with the experimental ordered moment's direction and high-temperature magnetic-susceptibility data, we have used a mean-field model with tetragonal CEF and exchange interactions to gain insight into the CEF scheme and anisotropy of the CEF ground-state wave function when Cd and Ir are introduced into C e 2 R h I n 8 . Consistent with previous work, we find that Cd doping in C e 2 R h I n 8 tends to rotate the magnetic moment toward the a b plane and lower the energy of the CEF excited states' levels. Interestingly, the presence of Ir also rotates the magnetic moment towards the a b plane although its connection to the CEF overall splitting evolution for the y = 0 samples may not be straightforward. These findings may shed light on the origin of the disordered spin-glass phase on the Ir-rich side of the phase diagram and also indicate that the C e 2 M I n 8 compounds may not follow exactly the same Rh-Ir CEF effects trend established for the C e 2 M I n 5 compounds.
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Affiliation(s)
- D S Christovam
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
| | - G S Freitas
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
| | - M M Piva
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - J C Souza
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
| | - M O Malcolms
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
| | - O L Canton
- Instituto de Física Teórica, Universidade Estadual Paulista-UNESP, São Paulo-SP, 01140-070, Brazil
| | - J B Leão
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - W Ratcliff
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - J W Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - C Adriano
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
| | - P G Pagliuso
- Instituto de Física "Gleb Wataghin," UNICAMP, Campinas-SP, 13083-970, Brazil
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Freitas GS, Piva MM, Grossi R, Jesus CBR, Souza JC, Christovam DS, Oliveira NF, Leão JB, Adriano C, Lynn JW, Pagliuso PG. Tuning the crystalline electric field and magnetic anisotropy along the CeCuBi2-xSbx series. Phys Rev B 2020; 102:10.1103/PhysRevB.102.115129. [PMID: 37720400 PMCID: PMC10502689 DOI: 10.1103/physrevb.102.115129] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
We have performed X-ray powder diffraction, magnetization, electrical resistivity, heat capacity and inelastic neutron scattering (INS) to investigate the physical properties of the intermetallic series of compounds CeCuBi 2 - x Sb x . These compounds crystallize in a tetragonal structure with space group P 4 ∕ n m m and present antiferromagnetic transition temperatures ranging from 3.6 K to 16 K. Remarkably, the magnetization easy axis changed along the series, which is closely related to the variations of the tetragonal crystalline electric field (CEF) parameters. This evolution was analyzed using a mean field model, which included an anisotropic nearest-neighbor interactions and the tetragonal CEF Hamiltonian. We obtained the CEF parameters by fitting the magnetic susceptibility data with the constraints given by the INS measurements. More broadly, we discuss how this CEF evolution can affect the Kondo physics and the search for a superconducting state in this family.
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Affiliation(s)
- G. S. Freitas
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
| | - M. M. Piva
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
| | - R. Grossi
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
| | - C. B. R. Jesus
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
- Programa de Pós-Graduação em Física, Campus Prof. José Aluísio de Campos, UFS, 49100-000, São Cristóvão, SE, Brazil
| | - J. C. Souza
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
| | - D. S. Christovam
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
| | - N. F. Oliveira
- Instituto de Física, Universidade de São Paulo, São Paulo-SP, 05508-090, Brazil
| | - J. B. Leão
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102
| | - C. Adriano
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
| | - J. W. Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102
| | - P. G. Pagliuso
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas-SP, 13083-859, Brazil
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Piva MM, Tartaglia R, Freitas GS, Souza JC, Christovam DS, Thomas SM, Leão JB, Ratcliff W, Lynn JW, Lane C, Zhu JX, Thompson JD, Rosa PFS, Adriano C, Granado E, Pagliuso PG. Electronic and magnetic properties of stoichiometric CeAuBi 2. Phys Rev B 2020; 101:10.1103/PhysRevB.101.214431. [PMID: 34141976 PMCID: PMC8207490 DOI: 10.1103/physrevb.101.214431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report the electronic and magnetic properties of stoichiometric CeAuBi2 single crystals. At ambient pressure, CeAuBi2 orders antiferromagnetically below a Néel temperature (TN ) of 19 K. Neutron diffraction experiments revealed an antiferromagnetic propagation vector τ ^ = [ 0 , 0 , 1 ∕ 2 ] , which doubles the paramagnetic unit cell along the c axis. At low temperatures several metamagnetic transitions are induced by the application of fields parallel to the c axis, suggesting that the magnetic structure of CeAuBi2 changes as a function of field. At low temperatures, a linear positive magnetoresistance may indicate the presence of band crossings near the Fermi level. Finally, the application of external pressure favors the antiferromagnetic state, indicating that the 4f electrons become more localized.
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Affiliation(s)
- M. M. Piva
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany
| | - R. Tartaglia
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
| | - G. S. Freitas
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
| | - J. C. Souza
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
| | - D. S. Christovam
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
| | - S. M. Thomas
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J. B. Leão
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - W. Ratcliff
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - J. W. Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - C. Lane
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J.-X. Zhu
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J. D. Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P. F. S. Rosa
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C. Adriano
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
| | - E. Granado
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
| | - P. G. Pagliuso
- Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo, Brazil
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Kaneko UF, Piva MM, Jesus CBR, Saleta ME, Urbano RR, Pagliuso PG, Granado E. Evidence of precursor orthorhombic domains well above the electronic nematic transition temperature in Sr(Fe 1-x Co x ) 2As 2. J Phys Condens Matter 2019; 31:495402. [PMID: 31284273 DOI: 10.1088/1361-648x/ab2ffc] [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: 06/09/2023]
Abstract
Raman scattering, synchrotron x-ray diffraction, specific heat, resistivity and magnetic susceptibility measurements were performed in Sr(Fe1-x Co x )2As2 [[Formula: see text]] single crystals with superconducting critical temperature [Formula: see text] K and two additional transitions at 132 and 152 K observed in both specific heat and resistivity data. A quasielastic Raman signal with B 2g symmetry (tetragonal cell) associated with electronic nematic fluctuations is observed. Crucially, this signal shows maximum intensity at [Formula: see text] K, marking the nematic transition temperature. X-ray diffraction shows evidence of coexisting orthorhombic and tetragonal domains between [Formula: see text] and [Formula: see text] ∼ 152 K, implying that precursor orthorhombic domains emerge over an extended temperature range above [Formula: see text]. While the height of the quasielastic Raman peak is insensitive to [Formula: see text], the temperature-dependence of the average nematic fluctuation rate indicates a slowing down of the nematic fluctuations inside the precursor orthorhombic domains. These results are analogous to those previously reported for the LaFeAsO parent oxypnictide (Kaneko et al 2017 Phys. Rev. B 96 014506). We propose a scenario where the precursor orthorhombic phase may be generated within the electronically disordered regime ([Formula: see text]) as long as the nematic fluctuation rate is sufficiently small in comparison to the optical phonon frequency range. In this regime, the local atomic structure responds adiabatically to the electronic nematic fluctuations, creating a net of orthorhombic clusters that, albeit dynamical for [Formula: see text], may be sufficiently dense to sustain long-range phase coherence in a diffraction process up to [Formula: see text].
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Affiliation(s)
- U F Kaneko
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo 13083-100, Brazil
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Buffoni L, Piva MM, Baska P, Januszkiewicz K, Norbury LJ, Prior KC, Dezen D, Silva AS, Wedrychowicz H, Mendes RE. Immunization with the recombinant myosin regulatory light chain (FhrMRLC) in Adjuplex® adjuvant elicits a Th1-biased immune response and a reduction of parasite burden in Fasciola hepatica infected rats. Parasitol Int 2019; 75:102037. [PMID: 31841659 DOI: 10.1016/j.parint.2019.102037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/07/2019] [Accepted: 12/07/2019] [Indexed: 01/22/2023]
Abstract
The aim of this study was to assess the immune response and the protective efficacy elicited by the vaccination with the recombinant Fasciola hepatica myosin regulatory light chain (FhrMRLC) in Adjuplex® adjuvant against the infection with F. hepatica in rats. Four groups of 15 animals each were used for the study, one group was immunized with the recombinant F. hepatica MRLC in Adjuplex® adjuvant and the other groups remained as adjuvant, positive and negative control groups. The parasitological study showed that a statistically significant reduction of 65.1% and 82.1% in fluke burden and fecal egg count, respectively, was detected in vaccinated animals. In addition, vaccination with FhrMRLC induced a well-defined humoral and cellular immune response characterized by a significant production of specific IgG and IL-2, IL-12, TNF-α and IFN-γ; which confirms the immunogenic capacity of the FhrMRLC.
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Affiliation(s)
- L Buffoni
- Department of Animal Health, Faculty of Veterinary, University of Cordoba, Campus de Rabanales, Ctra. Madrid-Cádiz km 376, 14014 Córdoba, Spain.
| | - M M Piva
- Laboratory of Veterinary Pathology, Federal Institute of Santa Catarina (IFC), Rod. SC 283, km 08, CP 58, Concórdia, SC 89703-720, Brazil
| | - P Baska
- Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), 8 Ciszewkiego, 02-786 Warsaw, Poland
| | - K Januszkiewicz
- Witold Stefański Institute of Parasitology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, Poland
| | - L J Norbury
- School of Science, RMIT University, Bundoora 3083, Victoria, Australia
| | - K C Prior
- Laboratory of Veterinary Microbiology, Federal Institute of Santa Catarina (IFC), Rod. SC 283, km 08, CP 58, Concórdia, SC 89703-720, Brazil
| | - D Dezen
- Laboratory of Veterinary Microbiology, Federal Institute of Santa Catarina (IFC), Rod. SC 283, km 08, CP 58, Concórdia, SC 89703-720, Brazil
| | - A S Silva
- Department of Animal Science, Santa Catarina State University (UDESC), Sete de Setembro 77D, Chapecó, SC 89806-152, Brazil
| | - H Wedrychowicz
- Witold Stefański Institute of Parasitology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, Poland
| | - R E Mendes
- Laboratory of Veterinary Pathology, Federal Institute of Santa Catarina (IFC), Rod. SC 283, km 08, CP 58, Concórdia, SC 89703-720, Brazil
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Piva MM, Ajeesh MO, Christovam DS, Dos Reis RD, Jesus CBR, Rosa PFS, Adriano C, Urbano RR, Nicklas M, Pagliuso PG. High-pressure studies on heavy-fermion antiferromagnet CeCuBi 2. J Phys Condens Matter 2018; 30:375601. [PMID: 30074484 DOI: 10.1088/1361-648x/aad7d8] [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: 06/08/2023]
Abstract
We report in-plane electrical resistivity studies of CeCuBi2 and LaCuBi2 single crystals under applied pressure. At ambient pressure, CeCuBi2 is a c-axis Ising antiferromagnet with a transition temperature [Formula: see text] K. In a magnetic field applied along the c-axis at [Formula: see text] K a spin-flop transition takes place [Formula: see text] T. Applying pressure on CeCuBi2 suppresses T N at a slow rate. [Formula: see text] extrapolates to zero temperature at [Formula: see text] GPa. The critical field of the spin-flop transition [Formula: see text] displays a maximum of 6.8 T at [Formula: see text] GPa. At low temperatures, a zero-resistance superconducting state emerges upon the application of external pressure having a maximum T c of 7 K at 2.6 GPa in CeCuBi2. High-pressure electrical-resistivity experiments on the non-magnetic reference compound LaCuBi2 reveal also a zero resistance state with similar critical temperatures in the same pressure range as CeCuBi2. The great similarity between the superconducting properties of both materials and elemental Bi suggests a common origin of the superconductivity. We discuss that the appearance of this zero resistance state superconductivity may be related to the Bi layers present in the crystalline structure of both compounds and, therefore, could be intrinsic to CeCuBi2 and LaCuBi2, however further experiments under pressure are necessary to clarify this issue.
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Affiliation(s)
- M M Piva
- Instituto de Física 'Gleb Wataghin', UNICAMP, 13083-859, Campinas, SP, Brazil. Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany
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Piva MM, Besser M, Mydeen K, Garitezi TM, Rosa PFS, Adriano C, Grant T, Fisk Z, Urbano RR, Nicklas M, Pagliuso PG. Combined external pressure and Cu-substitution studies on BaFe₂As₂ single crystals. J Phys Condens Matter 2015; 27:145701. [PMID: 25786492 DOI: 10.1088/0953-8984/27/14/145701] [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: 06/04/2023]
Abstract
We report a combined study of external pressure and Cu-substitution on BaFe2As2 single crystals grown by the in-flux technique. At ambient pressure, the Cu-substitution is known to suppress the spin density wave (SDW) phase in pure BaFe2As2(T(SDW) ≈ 140 K) and to induce a superconducting (SC) dome with a maximum transition temperature T(c)(max) ≃ 4.2 K. This T(c)(max) is much lower than the T(c) ∼ 15-28 K achieved in the case of Ru, Ni and Co substitutions. Such a lower T(c) is attributed to a Cu(2+) magnetic pair-breaking effect. The latter is strongly suppressed by applied pressure, as shown herein, Tc can be significantly enhanced by applying high pressures. In this work, we investigated the pressure effects on Cu(2+) magnetic pair-breaking in the BaFe(2-x)Cu(x)As2 series. Around the optimal concentration (x(opd) = 0.11), all samples showed a substantial increase of T(c) as a function of pressure. Yet for those samples with a slightly higher doping level (over-doped regime), T(c) presented a dome-like shape with maximum T(c) ≃ 8 K. Remarkably interesting, the under-doped samples, e.g. x = 0.02 display a maximum pressure induced T(c) ≃ 30 K which is comparable to the maximum T(c)'s found for the pure compound under external pressures. Furthermore, the magnetoresistance effect as a function of pressure in the normal state of the x = 0.02 sample also presented an evolution consistent with the screening of the Cu(2+) local moments. These findings demonstrate that the Cu(2+) magnetic pair-breaking effect is completely suppressed by applying pressure in the low concentration regime of Cu(2+) substituted BaFe2As2.
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Affiliation(s)
- M M Piva
- Instituto de Física 'Gleb Wataghin', UNICAMP, Campinas-SP 13083-859, Brazil. Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany
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9
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Rosa PFS, Adriano C, Garitezi TM, Piva MM, Mydeen K, Grant T, Fisk Z, Nicklas M, Urbano RR, Fernandes RM, Pagliuso PG. Possible unconventional superconductivity in substituted BaFe2As2 revealed by magnetic pair-breaking studies. Sci Rep 2014; 4:6252. [PMID: 25176407 PMCID: PMC4150111 DOI: 10.1038/srep06252] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [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: 02/13/2014] [Accepted: 07/15/2014] [Indexed: 11/28/2022] Open
Abstract
The possible existence of a sign-changing gap symmetry in BaFe2As2-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe1.9M0.1As2 (M = Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for M = Cu and Mn compounds, which display very low SC transition temperature (Tc) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of Tc cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials.
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Affiliation(s)
- P F S Rosa
- 1] Instituto de Física "Gleb Wataghin", UNICAMP, Campinas-SP, 13083-859, Brazil [2] University of California, Irvine, California 92697-4574, USA
| | - C Adriano
- Instituto de Física "Gleb Wataghin", UNICAMP, Campinas-SP, 13083-859, Brazil
| | - T M Garitezi
- Instituto de Física "Gleb Wataghin", UNICAMP, Campinas-SP, 13083-859, Brazil
| | - M M Piva
- 1] Instituto de Física "Gleb Wataghin", UNICAMP, Campinas-SP, 13083-859, Brazil [2] Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany
| | - K Mydeen
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany
| | - T Grant
- University of California, Irvine, California 92697-4574, USA
| | - Z Fisk
- University of California, Irvine, California 92697-4574, USA
| | - M Nicklas
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany
| | - R R Urbano
- Instituto de Física "Gleb Wataghin", UNICAMP, Campinas-SP, 13083-859, Brazil
| | - R M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - P G Pagliuso
- Instituto de Física "Gleb Wataghin", UNICAMP, Campinas-SP, 13083-859, Brazil
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