Available on-demand - S.EL12.04.12
Electrical and Magnetic Properties of Thin Single Crystal Cr2O3 Films
Nguyen Vu1,Xiangpeng Luo1,Steve Novakov1,Wencan Jin2,Johanna Nordlander3,Peter Meisenheimer1,Morgan Trassin3,Liuyan Zhao1,John Heron1
University of Michigan1,Auburn University2,ETH Zürich3
Magnetoelectric materials have been of great interest due to their potential for low-power spintronic devices via the electric field switching of magnetization. Antiferromagnet Cr2O3 is one of a very few room temperature magnetoelectrics and possesses unique properties such as uncompensated surface spins and perpendicular magnetic anisotropy.  Since the first demonstration of the electric field control of exchange bias in bulk single crystal Cr2O3 heterostructures , intense effort has focused the demonstration of magnetoelectric switching using Cr2O3 thin films at room temperature. [3,4] The existence of twin domains in thin films grown on metallic electrodes, however, leads to high leakage current and dielectric breakdown fields that can only be circumvented by growing rather thick films (250-500 nm). [4,5] By using an isostructural epitaxial oxide electrode, V2O3, recent studies have shown the reduction and even possible elimination of twin domains in Cr2O3 films.  Dielectric and magnetoelectric switching studies of 200 nm thick films show bulk like performance, however, for next generation logic and memory the films must be scaled down. 
Here we present an investigation of the electrical endurance and magnetic properties of very thin (30-60 nm) single crystal Cr2O3 films grown by pulsed laser deposition onto V2O3 buffered (0001) oriented Al2O3 substrates. Our results show that 60 nm single crystal thin film has bulk-like resistivity ( 1012 cm) and significantly improved breakdown voltage (150-300 MV/m). Using magnetometry, we investigate exchange bias of thin film Cr2O3/ferromagnet heterostructure. The blocking temperature is found to be at 285 K which is higher compared to twinned films with similar or greater thickness in literature.  Further, Second Harmonic Generation confirms bulk magnetoelectric order of our single crystal thin film at room temperature. These results indicate the importance of crystallinity to realize bulk like properties in very thin films at room temperature.
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