Electric Control Of Magnetic Properties In Epitaxially Grown FeRh/MgO/PMN-PT Heterostructures

Cs Cl-type Fe Rh alloy is antiferromagnetic(AF)at room temperature,and it undergoes a peculiar first-order phase transition to a ferromagnetic(FM)phase upon heating.Fe Rh in the form of thin films has attracted extensive attention for its potential applications in spintronic devices.In this work,thanks to the insertion of a thin Mg O buffer layer,we realized a nice epitaxial growth of Fe Rh(001)film on 0.7[Pb(Mg_1/3Nb_2/3)O₃]-0.3[Pb Ti O₃](PMN-PT)substrate by using a magnetron sputtering system,and great result of Electric control of magnetic properties in epitaxially grown Fe Rh/Mg O/PMN-PT heterostructures was realized.The main results of this work are as follows:We epitaxially grew the metamagnetic Fe Rh films on ferroelectric(FE)PMN-PT(001)substrates by post-annealing and investigated the electric control of magnetic properties.An Mg O buffer layer is inserted to reduce the considerably large lattice mismatch of 5.44%between Fe Rh and PMN-PT,leading to a nice epitaxial growth with a relationship of Fe Rh[110](001)||Mg O[100](001)||PMN-PT[100](001).The as-grown Fe Rh film shows a typical antiferromagnetic-to-ferromagnetic(AF-FM)phase transition by means of varying the temperature.Because a growth-induced uniaxial magnetic anisotropy is superimposed on the in-plane four-fold magnetocrystalline anisotropy,the epitaxial Fe Rh film displays different kinds of multi-step hysteresis loops at various field orientations.An electric field applied on the PMN-PT substrate can remarkably increase the coercivity of Fe Rh film,which presents a butterfly type shape,indicating a strain-mediated magnetoelectric coupling.Because of the inhibitory effect of the remnant compressive strain on the phase transition,the critical transition temperature and the magnetization are obviously enhanced and reduced,respectively,after removing the electric effect.Polycrystalline Fe Rh/PMN-Pt heterostructures and single crystal Fe Rh/Mg O/PMN-PT heterostructures were prepared by in-situ annealing.The insertion of a thin Mg O buffer layer lead to a nice epitaxial growth of Fe Rh(001)film on PMN-PT substrates and a inhibitory effect on the element diffusion at the Fe Rh/PMN-PT interface.Similar result of electric control of magnetic properties on the single crystal Fe Rh prepared by post-annealing has also been observed.