Continuous control of classical-quantum crossover by external high pressure in the coupled chain compound CsCuCl$_3$

TL;DR

This study demonstrates a method to actively control the classical-quantum crossover in magnetic insulators using external pressure, exemplified by high-pressure magnetization measurements on CsCuCl$_3$, revealing a continuous evolution from semi-classical to quantum regimes.

Contribution

It introduces a novel approach to tune quantum correlations in magnetic materials via external pressure, enabling control over the classical-quantum crossover in coupled-chain compounds.

Findings

Magnetization evolves continuously from semi-classical to quantum regimes with pressure.

Pressure effectively 'squashes' spin chains, altering quantum correlations.

The method provides a new way to access tunable quantum states in 2D spin systems.

Abstract

In solid materials, the parameters relevant to quantum effects, such as the spin quantum number, are basically determined and fixed at the chemical synthesis, which makes it challenging to control the amount of quantum correlations. We propose and demonstrate a method for active control of the classical-quantum crossover in magnetic insulators by applying external pressure. As a concrete example, we perform high-field, high-pressure measurements on CsCuCl$_3$, which has the structure of weakly-coupled spin chains. The magnetization process experiences a continuous evolution from the semi-classical realm to the highly-quantum regime with increasing pressure. Based on the idea of "squashing" the spin chains onto a plane, we characterize the change in the quantum correlations by the change in the value of the local spin quantum number of an effective two-dimensional model. This opens a way to access the tunable classical-quantum crossover of two-dimensional spin systems by using alternative systems of coupled-chain compounds.