Isothermal magnetocaloric effect in the vicinity of the Lifshitz point in Mn_{0.9}Co_{0.1}P

TL;DR

This study investigates the magnetic phase diagram and magnetocaloric effects near the Lifshitz point in Mn0.9Co0.1P, revealing a new phase and critical behaviors through experimental measurements and phenomenological modeling.

Contribution

It provides detailed experimental data on the phase diagram and introduces a phenomenological theory to describe critical lines and magnetocaloric properties near the Lifshitz point.

Findings

Confirmation of the phase diagram shape and characteristic temperatures.

Identification of a new phase with larger existence range.

Observation of a sharp peak in the imaginary susceptibility at the Lifshitz point.

Abstract

The magnetic field - temperature (B - T) phase diagram of the Mn0.9Co0.1P single crystal is studied in the vicinity of the Lifshitz point by means of isothermal magnetocaloric coefficient (Mt) and AC susceptibility measurements. Results confirm previously reported shape of the B - T phase diagram and locations of characteristic temperatures and fields. At the Curie temperature (Tc) the critical exponent w, which describes a singularity of Mt as a function of magnetic field (Mt \propto B^-w), is estimated for B parallel to the easy axis to be equal to w \approx 0.35. Below Tc an evidence of a new enigmatic phase, reported already for pure MnP, is found in susceptibility data also for Mn0.9Co0.1P. However, the range of existence of this phase is significantly larger here, than in MnP. At the Lifshitz point there is observed a sharp peak in the imaginary part of the magnetic susceptibility. A phenomenological theory is introduced to describe the field dependence of the critical lines from the disordered phase (paramagnetic) to ordered phases (ferromagnetic and modulated). The temperature and field dependences of the magnetocaloric coefficient and susceptibility are also calculated within the same framework.