Exchange randomness and spin dynamics in the frustrated magnetic Keplerate {W72V30}

TL;DR

This study investigates the complex spin dynamics and magnetic properties of the frustrated polyoxometalate {W72V30}, revealing broad exchange interactions and slow spin relaxation phenomena through experimental and theoretical analyses.

Contribution

It introduces a model with a broad distribution of exchange interactions to explain the magnetic behavior of {W72V30}, advancing understanding of frustrated spin systems.

Findings

Magnetization increases monotonically up to 50 T without staircase features.

Slow spin dynamics observed at low temperatures.

Broad distribution of exchange interactions explains experimental data.

Abstract

The magnetic properties and spin dynamics of the spin frustrated polyoxometalate {W72V30}, where 30 V^{4+} ions (s = 1/2) occupy the sites of an icosidodecahedron, have been investigated by low temperature magnetization, magnetic susceptibility, proton and vanadium nuclear magnetic resonance, and theoretical studies. The field-dependent magnetization at 0.5 K increases monotonically up to 50 T without any sign of staircase behavior. This low-temperature behavior cannot be explained by a Heisenberg model based on a single value of the nearest-neighbor exchange coupling. We analyze this behavior upon assuming a rather broad distribution of nearest-neighbor exchange interactions. Slow spin dynamics of {W72V30} at low temperatures is observed from the magnetic field and temperature dependence of nuclear spin-lattice relaxation rate 1/T_1 measurements.