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Observations of the effect of strong Pauli paramagnetism on the vortex lattice in superconducting CeCu2Si2

Campillo, E. LU ; Riyat, R. ; Pollard, S. ; Jefferies, P. ; Holmes, A. T. ; Cubitt, R. ; White, J. S. ; Gavilano, J. ; Huesges, Z. and Stockert, O. , et al. (2021) In Physical Review B 104(18).
Abstract

We present the results of a study of the vortex lattice in the heavy fermion superconductor CeCu2Si2, using small-angle neutron scattering (SANS). In this material at temperatures well below Tc∼0.6 K, the value of the upper critical field Bc2∼2.2 T is strongly limited by the Pauli paramagnetism of the heavy fermions. In this temperature region, our SANS data show an increase in the magnetization of the flux line cores with field, followed by a rapid fall near Bc2. This behavior is the effect of Pauli paramagnetism and we present a theory-based model, which can be used to describe this effect in a range of materials. The pairing in CeCu2Si2 appears to arise from the effect of magnetic fluctuations, but the evidence for a d-wave order... (More)

We present the results of a study of the vortex lattice in the heavy fermion superconductor CeCu2Si2, using small-angle neutron scattering (SANS). In this material at temperatures well below Tc∼0.6 K, the value of the upper critical field Bc2∼2.2 T is strongly limited by the Pauli paramagnetism of the heavy fermions. In this temperature region, our SANS data show an increase in the magnetization of the flux line cores with field, followed by a rapid fall near Bc2. This behavior is the effect of Pauli paramagnetism and we present a theory-based model, which can be used to describe this effect in a range of materials. The pairing in CeCu2Si2 appears to arise from the effect of magnetic fluctuations, but the evidence for a d-wave order parameter is rather weak. We find that the vortex lattice structure in CeCu2Si2 is close to regular hexagonal. There are no phase transitions to square or rhombic structures; such transitions are expected for d-wave superconductors and observed in CeCoIn5; however, the temperature dependence of the SANS intensity indicates that both large and small gap values are present, most likely due to multiband s-wave superconductivity, rather than a nodal gap structure.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B
volume
104
issue
18
article number
A99
publisher
American Physical Society
external identifiers
  • scopus:85119331082
ISSN
2469-9950
DOI
10.1103/PhysRevB.104.184508
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2021 authors. Published by the American Physical Society.
id
3f0d78fa-f8bb-47b5-a637-b96860e80f56
date added to LUP
2021-12-20 16:31:28
date last changed
2023-11-09 02:23:13
@article{3f0d78fa-f8bb-47b5-a637-b96860e80f56,
  abstract     = {{<p>We present the results of a study of the vortex lattice in the heavy fermion superconductor CeCu2Si2, using small-angle neutron scattering (SANS). In this material at temperatures well below Tc∼0.6 K, the value of the upper critical field Bc2∼2.2 T is strongly limited by the Pauli paramagnetism of the heavy fermions. In this temperature region, our SANS data show an increase in the magnetization of the flux line cores with field, followed by a rapid fall near Bc2. This behavior is the effect of Pauli paramagnetism and we present a theory-based model, which can be used to describe this effect in a range of materials. The pairing in CeCu2Si2 appears to arise from the effect of magnetic fluctuations, but the evidence for a d-wave order parameter is rather weak. We find that the vortex lattice structure in CeCu2Si2 is close to regular hexagonal. There are no phase transitions to square or rhombic structures; such transitions are expected for d-wave superconductors and observed in CeCoIn5; however, the temperature dependence of the SANS intensity indicates that both large and small gap values are present, most likely due to multiband s-wave superconductivity, rather than a nodal gap structure. </p>}},
  author       = {{Campillo, E. and Riyat, R. and Pollard, S. and Jefferies, P. and Holmes, A. T. and Cubitt, R. and White, J. S. and Gavilano, J. and Huesges, Z. and Stockert, O. and Forgan, E. M. and Blackburn, E.}},
  issn         = {{2469-9950}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{18}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review B}},
  title        = {{Observations of the effect of strong Pauli paramagnetism on the vortex lattice in superconducting CeCu2Si2}},
  url          = {{http://dx.doi.org/10.1103/PhysRevB.104.184508}},
  doi          = {{10.1103/PhysRevB.104.184508}},
  volume       = {{104}},
  year         = {{2021}},
}