Magnetism and a field-cycling induced effect in staircase Kagom\'e antiferromagnet PbCu$_3$TeO$_7$ revealed by NMR

TL;DR

This study uses NMR to explore the magnetic properties of PbCu3TeO7, revealing intermediate frustration, strong interlayer coupling, and field-cycling effects linked to domain walls in this staircase Kagomé antiferromagnet.

Contribution

It provides the first detailed NMR analysis of PbCu3TeO7, highlighting hyperfine interactions, frustration level, and field-induced domain wall phenomena in this complex magnetic system.

Findings

High-temperature Knight shift indicates strong interlayer coupling.

Frustration factor suggests intermediate magnetic frustration.

Field cycling reveals domain wall contributions at low temperature.

Abstract

We report $^{125}$Te and $^{63,65}$Cu nuclear magnetic resonance (NMR) studies on single crystals of staircase Kagom\'e antiferromagnet PbCu3TeO7 ($T_{N1}\approx$ 36 K). A Curie constant as large as $\Theta$~140 K is obtained by a Curie-Weiss fitting of the high-temperature Knight shift. The frustration factor f (= $\Theta/T_N $)$\approx$ 4 implies intermediate frustration in this system. From the high-temperature Knight shift data of $^{125}$Te, its hyperfine coupling constant is estimated to be $^{125}A_{hf}$ = -67 kOe/${\mu}_B$, which suggests a strong interlayer coupling bridging the neighboring Kagom\'e layers. At $T$= 2 K, we find two types of zero-field NMR signals. One has no dependence on the history of the field treatment, which is consistent with Cu NMR signals from inequivalent Cu sites with different internal hyperfine fields. The other one is only seen after a field-cycling process, which is consistent with domain wall contributions in this frustrated antiferromagnet.