Enhancement of charge-neutral fermionic excitation near spin-flop transition\\ in magnetic Kondo material YbIr${}_3$Si${}_7$

Abstract

The new Kondo material YbIr${}_3$Si${}_7$, similar to other Kondo insulators, has been reported to exhibit charge-neutral fermionic excitations through measurements of specific heat and thermal conductivity at low temperatures. We performed ${}^{29}$Si-NMR on YbIr${}_3$Si${}_7$ to investigate the magnetic response of charge-neutral fermions from a microscopic perspective. In low magnetic fields parallel to the $c$ axis, a single NMR peak in the paramagnetic state splits into three peaks below $T_{\mathrm{N}}$. In contrast, only a slight shift of the single NMR peak was observed in high magnetic fields. This spectral change as a function of the $c$-axis magnetic field is interpreted as spin-flop transition, at which the magnetic moments oriented along the $c$ axis (AF-I phase) are rotated to the $ab$ plane with ferromagnetic component along the $c$-axis (AF-II phase). In the vicinity of the spin-flop magnetic field $H_{\mathrm{M}}$, nuclear spin-lattice relaxation rate $1/T_1$ was found to be proportional to temperature at low temperatures, indicating the existence of charge-neutral fermions. Furthermore, a peak of $1/T_1$ vs. the $c$-axis magnetic field suggests that the charge-neutral fermions in YbIr${}_3$Si${}_7$ are closely related to its magnetic properties. Our findings shed light on the origin of charge-neutral fermions in insulators.

5 pages, 3 figures

References in corpus (3)

• Quantum Oscillations of Electrical Resistivity in an Insulator
• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Field-Induced Instability of a Gapless Spin Liquid with a Spinon Fermi Surface

Cited by in corpus (1)

• Gapped Spin Excitation in Magnetic Ordered State on Yb-Based Zigzag Chain Compound YbAgSe2