Is the half-quantized thermal Hall plateau in alpha-RuCl3 reproducible? · revision history

Revision 2

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Title
Is the half-quantized thermal Hall plateau in $\alpha$-RuCl3 reproducible?
Plain
One group reported that the sideways heat flow stops changing with field at exactly half of a fundamental quantum value, the signature of a single Majorana edge channel. Other groups saw values near it without a flat plateau, or a strongly temperature-dependent signal, so it is unclear whether it is a real property of the material.
Precise
Test whether $\kappa_{xy}/T = (1/2)(\pi^2 k_B^2/3h)$ holds within 10 percent over a finite field range in $\alpha$-RuCl3 in the field-induced disordered regime (in-plane $H$ near 70 to 90 kOe, $T$ about 4 to 6 K), and whether it is independent of sample width and of $\kappa_{xx}$ as an edge mode requires. An answer is yes with reproducible data from independent groups, or a demonstration that the apparent plateau is an accidental crossing of a nonquantized phonon or magnon signal.
Settled by
Independent measurements on multiple samples of different widths and $\kappa_{xx}$ values, including constrictions, showing the plateau value and its size independence, or its absence.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
contested
Status note · changed
Revision 1: Reported by Kasahara et al. (Nature 2018) and Yokoi et al. (Science 2021); Bruin et al. (Nature Physics 2022) found $\kappa_{xy}/T$ near the half-quantized value over an extended region but without a strict plateau; Czajka et al. (Nature Materials 2023) found a strongly $T$-dependent kappa_xy/T and attributed it to topological magnons.
Revision 2: Reported by Kasahara et al. (Nature 2018) and Yokoi et al. (Science 2021); Bruin et al. (Nature Physics 2022) found $\kappa_{xy}/T$ near the half-quantized value over an extended region but without a strict plateau; Czajka et al. (Nature Materials 2023) found a strongly $T$-dependent $\kappa_{xy}/T$ and attributed it to topological magnons.
Posed since
2018

Decisions