Unusual spin pseudogap behavior in the spin web lattice Cu${}_3$TeO${}_6$ probed by ${}^{125}$Te nuclear magnetic resonance

Abstract

We present a ${}^{125}$Te nuclear magnetic resonance (NMR) study in the three-dimensional spin web lattice Cu${}_3$TeO${}_6$, which harbors topological magnons. The ${}^{125}$Te NMR spectra and the Knight shift $\mathcal{K}$ as a function of temperature show a drastic change at $T_{\text{S}}\sim 40$ K much lower than the Néel ordering temperature $T_{\text{N}}\sim 61$ K, providing evidence for the first-order structural phase transition within the magnetically ordered state. Most remarkably, the temperature dependence of the spin-lattice relaxation rate $T_1^{-1}$ unravels spin-gap-like magnetic excitations, which sharply sets in at $T^{\ast }\sim 75$ K, the temperature well above $T_{\text{N}}$. The spin gap behavior may be understood by weakly dispersive optical magnon branches of high-energy spin excitations originating from the unique corner-sharing Cu hexagon spin-1/2 network with low coordination number.

arXiv comment6 pages, 2 figures, published in Physical Review Research

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Cited by in corpus (1)

• Spin-Reorientation-Driven Linear Magnetoelectric Effect in Topological Antiferromagnet Cu${}_3$TeO${}_6$