Nature of the two superconducting phases of CeRh_2As_2 · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed
Revision 1: Nature of the two superconducting phases of CeRh2As2
Revision 2: Nature of the two superconducting phases of $\mathrm{CeRh_2As_2}$
Plain · changed
Revision 1: In CeRh2As2 a magnetic field along one crystal axis switches the superconductor from one state to another, possibly from even-parity to odd-parity pairing, made possible because each cerium layer lacks a center of inversion although the whole crystal has one.
Revision 2: In $\mathrm{CeRh_2As_2}$ a magnetic field along one crystal axis switches the superconductor from one state to another, possibly from even-parity to odd-parity pairing, made possible because each cerium layer lacks a center of inversion although the whole crystal has one.
Precise · changed · core
Revision 1: CeRh2As2 ($T_{c} \sim 0.26\ \mathrm{K}$) shows for $H \mid\mid c$ a transition at H* ~ 40 kG between a low-field phase SC1 and a high-field phase SC2 extending to H_c2 ~ 140 kG (Khim et al., Science 2021). Determine whether SC1 and SC2 are the even- and odd-parity states of locally noncentrosymmetric Ce layers, or whether H* is controlled by the quadrupole-density-wave or antiferromagnetic order found near or inside the superconducting phase. An answer identifies the order parameters of both phases by site-resolved NMR Knight shift, field-angle dependence of H*, and the relation of H* to the normal-state order.
Revision 2: $\mathrm{CeRh_2As_2}$ ($T_{c} \sim 0.26\ \mathrm{K}$) shows for $H \mid\mid c$ a transition at $H* \sim 40 \mathrm{kG}$ between a low-field phase SC1 and a high-field phase SC2 extending to $H_c2 \sim 140 \mathrm{kG}$ (Khim et al., Science 2021). Determine whether SC1 and SC2 are the even- and odd-parity states of locally noncentrosymmetric Ce layers, or whether $H*$ is controlled by the quadrupole-density-wave or antiferromagnetic order found near or inside the superconducting phase. An answer identifies the order parameters of both phases by site-resolved NMR Knight shift, field-angle dependence of $H*$, and the relation of $H*$ to the normal-state order.
Settled by
Site-resolved Knight shift in SC1 and SC2 plus a measurement showing whether $H*$ moves with the normal-state ordering field when that order is suppressed (by La substitution or pressure).
Kind
well-posed
Answer type
identification
References
(empty)
Literature status
contested
Status note
Field-angle data (Landaeta et al., PRX 2022) support an even-to-odd parity transition, while a possible quadrupole density wave (Hafner et al., PRX 2022) and antiferromagnetism inside the superconducting state offer alternative explanations.
Posed since
2021

Decisions