Exchange bias in Fe/Ir20Mn80 bilayers: Role of spin-glass like interface and bulk antiferromagnet spins

TL;DR

This study investigates the magnetic interface of Fe/Ir20Mn80 bilayers, revealing the roles of bulk antiferromagnetic spins and spin-glass-like interface in exchange bias behavior through various magnetic measurements.

Contribution

It provides new insights into the interface magnetic nature, highlighting the presence of spin-glass-like behavior and frozen/rotatable spins affecting exchange bias in Fe/Ir20Mn80 bilayers.

Findings

Exchange bias depends on Ir20Mn80 thickness, indicating bulk AFM contribution.

Spin-glass-like interface causes exponential decay of exchange bias with temperature.

Training effects suggest coexistence of frozen and rotatable spins at the interface.

Abstract

We have performed magnetic measurements like temperature (T), cooling field (HFC) dependence of exchange bias (EB) and training effect to investigate the magnetic nature of the interface of the Fe/Ir20Mn80 systems. Thin film bilayer samples of different thicknesses of Ir20Mn80 have been prepared by dc magnetron sputtering at room temperature. The variation of exchange bias field (HEB) with the increase in thickness of Ir20Mn80 predicts the antiferromagnet (AFM) bulk spins contribution to EB. Exponential decay of HEB and coercive field (HC) with temperature reveals the presence of spin glass (SG) like interface. Also, the decrease of HEB with increasing HFC confirms the SG like frustration at the interface. Further, the fitting of training effect experimental data envisages the presence of frozen and rotatable spins at the magnetically frustrated interface of these EB systems.