Field-induced magnetic instability within a superconducting condensate

Quantum materials that feature magnetic long-range order often reveal complex phase diagrams when localized electrons become mobile. In many materials magnetism is rapidly suppressed as electronic charges dissolve into the conduction band. In materials where magnetism persists, it is unclear how the magnetic properties are affected. Here we study the evolution of the magnetic structure in Nd1−xCexCoIn5 from the localized to the highly itinerant limit. We observe two magnetic ground states inside a heavy-fermion phase that are detached from unconventional superconductivity. The presence of two different magnetic phases provides evidence that increasing charge delocalization affects the magnetic interactions via anisotropic band hybridization. arXiv:1905.13219v1 [cond-mat.str-el]

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“…Left legend represent data from Ref 17,. the right legend are our data (the phase boundaries of x = 0.95 were taken from Ref 19…”

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confidence: 99%

Evolution of Magnetic Order from the Localized to the Itinerant Limit

et al. 2019

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“…4 for H|| [11 0]. It demonstrates that the magnetic Q 2 -domain gradually weakens with increasing magnetic field and is suppressed at µ 0 H d = 3.6(6) T. This is in strong contrast to the field dependence of the Q 1 -domain, whose intensity increases at small fields and reveals a broad maximum around µ 0 H ≈ 4 T [26].…”

Section: Fig 1 Displays Two Magnetic Bragg Peaks That Belongmentioning

confidence: 99%

“…4 compares the scaled, integrated intensity of the two magnetic domains, I Q1 and I Q2 , with the total integrated intensity I tot = I Q1 + I Q2 for H||[1 1 0]. This plot combines new measurements with those published earlier [26]. The normalization of the integrated intensity was chosen to have equal population at zero field, respecting the tetragonal symmetry.…”

Section: Fig 1 Displays Two Magnetic Bragg Peaks That Belongmentioning

confidence: 99%

“…The series Nd 1−x Ce x CoIn 5 reveals a competition between static magnetic order and superconductivity for x > 0.78 at zero field [25]. 5% Nd doped CeCoIn 5 , however, features an auxiliary field-induced magnetic phase (Q-phase) that is only stable within the superconducting condensate and that collapses in a first-order transition at the upper critical field [26]. This behavior provides evidence for a cooperative magneto-superconducting ground state in the Q-phase with a coupling that is similar to the one of undoped CeCoIn 5 .…”

Section: Introductionmentioning

confidence: 99%

“…This behavior provides evidence for a cooperative magneto-superconducting ground state in the Q-phase with a coupling that is similar to the one of undoped CeCoIn 5 . The high-field Q-phase of 5% Nd doped CeCoIn 5 is separated from its low-field SDWphase via a quantum phase transition at µ 0 H * ≈ 8 T [26]. Both magnetic phases feature the same amplitude modulated spin-density wave (SDW) order with an ordered magnetic moment, µ ≈ 0.15µ B , that is oriented along the c-axis.…”

Section: Introductionmentioning

confidence: 99%

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Distinct domain switching in Nd0.05Ce0.95CoIn5 at low and high fields

Mazzone

Yadav

Bartkowiak

et al. 2018

Sci Rep

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Nd0.05Ce0.95CoIn5 features a magnetic field-driven quantum phase transition that separates two antiferromagnetic phases with an identical magnetic structure inside the superconducting condensate. Using neutron diffraction we demonstrate that the population of the two magnetic domains in the two phases is affected differently by the rotation of the magnetic field in the tetragonal basal plane. In the low-field SDW-phase the domain population is only weakly affected while in the high-field Q-phase they undergo a sharp switch for fields around the a-axis. Our results provide evidence that the anisotropic spin susceptibility in both phases arises ultimately from spin-orbit interactions but are qualitatively different in the two phases. This provides evidence that the electronic structure is changed at the quantum phase transition, which yields a modified coupling between magnetism and superconductivity in the Q-phase.

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Direct measurement of the evolution of magnetism and superconductivity toward the quantum critical point

Higemoto

Yokoyama

Ito

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Nontrivial quantum states can be realized in the vicinity of the quantum critical point (QCP) in many strongly correlated electron systems. In particular, an emergence of unconventional superconductivity around the QCP strongly suggests that the quantum critical fluctuations play a central role in the superconducting pairing mechanism. However, a clear signature of the direct coupling between the superconducting pairing states and the quantum criticality has not yet been elucidated by the microscopic probes. Herein, we present muon spin rotation/relaxation and neutron diffraction measurements in the superconducting dome of CeCo(In 1 − x Zn x ) 5 . It was found that a magnetically ordered state develops at x ≥ 0.03, coexisting with the superconductivity. The magnitude of the ordered magnetic moment is continuously reduced with decreasing x , and it disappears below x ∼ 0.03, indicating a second-order phase transition and the presence of the QCP at this critical Zn concentration. Furthermore, the magnetic penetration depth diverges toward the QCP. These facts provide evidence for the intimate coupling between quantum criticality and Cooper pairing.

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Field-induced magnetic instability within a superconducting condensate

Abstract: Researchers found evidence for a quantum phase transition within a superconducting condensate.

Cited by 14 publications

References 40 publications

Evolution of Magnetic Order from the Localized to the Itinerant Limit

Evolution of Magnetic Order from the Localized to the Itinerant Limit

Distinct domain switching in Nd0.05Ce0.95CoIn5 at low and high fields

Direct measurement of the evolution of magnetism and superconductivity toward the quantum critical point

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