Experimental confirmation of spin gap in antiferromagnetic alternating spin-3/2 chain substances RCrGeO5 (R = Y or 154Sm) by inelastic neutron scattering experiments

TL;DR

This study experimentally confirms the existence of a spin gap in antiferromagnetic alternating spin-3/2 chain compounds RCrGeO5 using inelastic neutron scattering, expanding understanding of quantum spin systems beyond lower spin values.

Contribution

First experimental demonstration of a spin gap in antiferromagnetic spin-3/2 chain substances through neutron scattering and magnetization measurements.

Findings

Observed spin gap excitations in RCrGeO5

Established the dispersion relation of magnetic excitations

Confirmed antiferromagnetic alternating spin-3/2 chain system

Abstract

A spin-singlet ground state with a spin gap has been discovered in antiferromagnetic spin chain substances when the spin value is 1/2, 1 or 2. To find spin gap (singlet-triplet) excitations in spin-3/2 chain substances, we performed inelastic neutron scattering and magnetization measurements on {\it R}CrGeO$_5$ ({\it R} = Y or Sm) powders. As expected, we observed spin gap excitations and the dispersion relation of the lowest magnetic excitations. We proved that the spin system of Cr$^{3+}$ was an antiferromagnetic alternating spin-3/2 chain.