AC Susceptibility and Electron Spin Resonance Studies of Spin Dynamics in n Ba$_3$NbFe$_3$Si$_2$O$_{14}$: A Geometrically Frustrated Lattice

TL;DR

This study investigates the complex spin dynamics in a geometrically frustrated magnetic compound using ac susceptibility and ESR, revealing spin-glass behavior, multi-step ordering, and coexistence of short- and long-range magnetic order.

Contribution

It provides new insights into the spin fluctuations and ordering processes in a frustrated lattice, highlighting the coexistence of different magnetic states.

Findings

Large frequency dependence of ac susceptibility indicates spin-glass-like behavior.

ESR shows multi-step magnetic and spin chirality ordering.

Development of short-range spin clusters above 30 K and long-range order below 9.5 K.

Abstract

We report ac susceptibility and high-frequency electron spin resonance (ESR) measurements on the geometrically frustrated compound Ba$_3$NbFe$_3$Si$_2$O$_{14}$ with the N\'{e}el temperature $T_N=27 K$. An unusually large frequency-dependence of ac susceptibility in the temperature range of 20 - 100 K reveals a spin-glass-like behavior, signalling the presence of frustration related slow magnetic fluctuations. ESR experiments show a multi-step magnetic and spin chirality ordering process. For temperatures above 30 K, the weak temperature dependence of the ESR linewidth $\Delta H_{pp}\propto T^{-p}$ with $p=0.8$ evidences the development of short-range correlated spin clusters. The critical broadening with $p =1.8$, persisting down to 14 K, indicates the coexistence of the short-range ordered spin clusters within a helically ordered state. Below 9.5 K, the anomalously large decrease of the linewidth reveals the stabilization of a long-range ordered state with one chirality.