Competing magnetic phases in the frustrated spin-1/2 chain compound $\beta$-TeVO$_4$ probed by NMR

TL;DR

This study uses $^{17}$O NMR to explore the complex magnetic phases of the frustrated spin-1/2 chain compound $eta$-TeVO$_4$, revealing the nature of spin-stripe and high-field SDW phases influenced by anisotropy and interchain interactions.

Contribution

First comprehensive NMR analysis of $eta$-TeVO$_4$, elucidating the static and dynamic magnetic phases and their relation to theoretical models.

Findings

Confirmation of the dynamical spin-stripe phase.

Identification of an unusual SDW order in high magnetic fields.

Evidence of magnetic anisotropy stabilizing the SDW phase.

Abstract

In frustrated spin-1/2 chains the competition between the nearest- and next-nearest-neighbor exchange interactions leads to a rich phase diagram that becomes even richer in the presence of perturbations in their material realizations. These effects are still largely unexplored, so that new insight into static and dynamic magnetism, in particular by sensitive local probes, is highly desired. Here we present a comprehensive $^{17}$O nuclear magnetic resonance study of $\beta$-TeVO$_4$, where the anisotropy of the main exchange interactions and additional weak interchain exchange interactions complement the theoretical phase diagram. Our results confirm the dynamical nature of the intriguing spin-stripe phase that has been reported in previous studies. In addition, we find that the magnetic order in the high-field phase, which develops just below the magnetization saturation, is consistent with an unusual type of spin-density-wave (SDW) order with different alignments of the magnetic moments on the neighboring chains. This is reminiscent of the ordering in the SDW phase, realized in the absence of the magnetic field, and is thus most likely stabilized by magnetic anisotropy.