Observation of spin glass behavior in chiral Mn48Fe34Si18 with a β-Mn related structure

Johannes Kroder,Gerhard H Fecher,Walter Schnelle,Johannes Gooth,Claudia Felser

doi:10.1063/1.5089191

Johannes Kroder, Gerhard H Fecher + Show 3 more

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https://doi.org/10.1063/1.5089191

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Abstract

The ternary silicide system Fe-Mn-Si exhibits several complex magnetic phases and the chemical similarity of Fe and Mn enables these two elements to be mutually substituted over a wide compositional range. Because this substitution results in chemical disorder and often causes competing magnetic exchange interactions, frustrated spin glass ordering is expected to occur for some Fe-Mn-Si phases. However, the observation of a spin glass state within these alloys has been elusive to date. This paper reports magnetization and ac susceptibility measurements on Mn48Fe34Si18. The compound crystallizes in a Mn3IrSi-type structure, which is closely related to that of β-Mn. Typical spin glass behavior is observed at low temperatures. This comprises a bifurcation of field-cooled and zero-field-cooled magnetization, a displacement of the field-cooled hysteresis loop, magnetic relaxation, a memory effect, and a sharp, frequency-dependent cusp in the ac susceptibility at the freezing temperature. Mn48Fe34Si18 is demonstrated to be a canonical spin glass.

Highlights

The chemical similarity of manganese and iron, in particular, allows these two elements to be mutually substituted over a broad compositional range
A good starting point to search for the possible existence of the spin glass state is the β-Mn phase, which has a broad stability range in the phase diagram at elevated temperatures
Powder x-ray diffraction (XRD) and back scattering electron microscopy were used to confirm that the sample is single phase

Summary

Introduction

The chemical similarity of manganese and iron, in particular, allows these two elements to be mutually substituted over a broad compositional range. Spin glasses are magnetically frustrated systems with a multidegenerate ground state.6–8 Below the freezing temperature Tf the spins order in a random, non-coplanar manner. Because the spin glass state is metastable, this ordering is highly sensitive to the history of temperature and applied magnetic field.

Results

Conclusion