Observation of thermodynamics originating from a mixed-spin ferromagnetic chain

TL;DR

This study reports the synthesis and analysis of a new mixed-spin ferromagnetic chain compound, revealing thermodynamic behaviors such as phase transitions and specific heat features through experimental and computational methods.

Contribution

The paper introduces a novel organic radical-based compound forming a mixed-spin ferromagnetic chain and provides detailed thermodynamic analysis using quantum Monte Carlo and spin-wave theories.

Findings

Ferromagnetic behavior confirmed by magnetic susceptibility.

Double-peak structure in specific heat indicating phase transition.

Quantum Monte Carlo explains thermodynamic features.

Abstract

We present a model compound that forms a mixed-spin ferromagnetic chain. Our material design, based on the organic radicals, affords a verdazyl-based complex (p-Py-V)2[Mn(hfac)2]. The molecular orbital calculations of the compound indicate the formation of a mixed spin-(1/2, 1/2, 5/2) ferromagnetic chain. The temperature dependence of magnetic susceptibility reveals its ferromagnetic behavior. The magnetic specific heat exhibits a double-peak structure and indicates a phase transition at the low-temperature peak. The observed characteristics are explained using the quantum Monte Carlo calculations. Furthermore, the modified spin-wave theory verifies that the double-peak structure of the specific heat significantly reflects the relative ration of the acoustic excitation band and the optical excitation gap.