TY - JOUR
T1 - Origin of the non-Fermi-liquid behavior in CeRh2As2
AU - Khanenko, P.
AU - Hafner, D.
AU - Semeniuk, K.
AU - Banda, J.
AU - Lühmann, T.
AU - Bärtl, F.
AU - Kotte, T.
AU - Wosnitza, J.
AU - Zwicknagl, G.
AU - Geibel, C.
AU - Landaeta, J. F.
AU - Khim, S.
AU - Hassinger, E.
AU - Brando, M.
N1 - Publisher Copyright:
© 2025 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.
PY - 2025/1/15
Y1 - 2025/1/15
N2 - Unconventional superconductivity in heavy-fermion systems appears often near magnetic quantum critical points (QCPs). This seems to be the case also for CeRh2As2 (Tc ≈0.31 K). CeRh2As2 shows two superconducting (SC) phases, SC1 and SC2, for a magnetic field along the c axis of the tetragonal unit cell, but only the SC1 phase is observed for a field along the basal plane. Furthermore, another ordered state (phase I) is observed below T0≈0.48K whose nature is still unclear: Thermodynamic and magnetic measurements pointed to a nonmagnetic multipolar state, but recent μSR and nuclear quadrupole resonance/nuclear magnetic resonance (NMR) experiments have clearly detected antiferromagnetic (AFM) order below T0. Also, quasi-two-dimensional AFM fluctuations were observed in NMR and neutron-scattering experiments above T0. The proximity of a QCP is indicated by non-Fermi-liquid (NFL) behavior observed above the ordered states in both specific heat C(T)/T∝T-0.6 and resistivity ρ(T)∝T. These T dependencies are not compatible with any generic AFM QCP. Because of the strong magnetic-field anisotropy of both the SC phase and phase I, it is possible to study a field-induced SC QCP as well as a phase-I QCP by varying the angle α between the field and the c axis. Thus, by examining the behavior of the electronic specific-heat coefficient C(T)/T across these QCPs, we can determine which phase is associated with the NFL behavior. Here, we present low-temperature specific-heat measurements taken in a magnetic field as high as 21 T applied at several angles α. We observe that the NFL behavior very weakly depends on the field and the angle α, a result that is at odds with observations in standard magnetic QCPs. This suggests a nonmagnetic origin of the quantum critical fluctuations.
AB - Unconventional superconductivity in heavy-fermion systems appears often near magnetic quantum critical points (QCPs). This seems to be the case also for CeRh2As2 (Tc ≈0.31 K). CeRh2As2 shows two superconducting (SC) phases, SC1 and SC2, for a magnetic field along the c axis of the tetragonal unit cell, but only the SC1 phase is observed for a field along the basal plane. Furthermore, another ordered state (phase I) is observed below T0≈0.48K whose nature is still unclear: Thermodynamic and magnetic measurements pointed to a nonmagnetic multipolar state, but recent μSR and nuclear quadrupole resonance/nuclear magnetic resonance (NMR) experiments have clearly detected antiferromagnetic (AFM) order below T0. Also, quasi-two-dimensional AFM fluctuations were observed in NMR and neutron-scattering experiments above T0. The proximity of a QCP is indicated by non-Fermi-liquid (NFL) behavior observed above the ordered states in both specific heat C(T)/T∝T-0.6 and resistivity ρ(T)∝T. These T dependencies are not compatible with any generic AFM QCP. Because of the strong magnetic-field anisotropy of both the SC phase and phase I, it is possible to study a field-induced SC QCP as well as a phase-I QCP by varying the angle α between the field and the c axis. Thus, by examining the behavior of the electronic specific-heat coefficient C(T)/T across these QCPs, we can determine which phase is associated with the NFL behavior. Here, we present low-temperature specific-heat measurements taken in a magnetic field as high as 21 T applied at several angles α. We observe that the NFL behavior very weakly depends on the field and the angle α, a result that is at odds with observations in standard magnetic QCPs. This suggests a nonmagnetic origin of the quantum critical fluctuations.
UR - http://www.scopus.com/inward/record.url?scp=85216921615&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.111.045162
DO - 10.1103/PhysRevB.111.045162
M3 - Article
AN - SCOPUS:85216921615
SN - 2469-9950
VL - 111
JO - Physical Review B
JF - Physical Review B
IS - 4
M1 - 045162
ER -