Stabilizing New States Via Heteroepitaxy of Magnetically Frustrated Materials

1. Yuri Suzuki, University of California-Berkeley, DMR 1104401 We have recently demonstrated that heteroepitaxy of magnetically frustrated materials can give rise to the stabilization of novel ground states not observable in the bulk. Heteroepitaxy lifts magnetic frustration through the modification of exchange interactions. More specifically we demonstrate that by decreasing the tetragonality of the unit cell of magnetically frustrated CuCr2O4 and thus yielding greater collinear alignment between the Cr3+ moments, we heal the frustration of the magnetic moments in CCO thin films and significantly enhance the magnetization compared to that of bulk. Stabilizing New States Via Heteroepitaxyof Magnetically Frustrated Materials Magnetically frustrated CuCr2O4 with spinel structureshowing the edge-sharing Cr3+octahedra (yellow) formed by oxygen anions (red, size reduced for clarity); the Cr3+octahedra are corner shared with the Cu2+tetrahedra (blue). (a) Hysteresis loops of CuCr2O4 on different substrates indicate the effect of lattice distortions on the bulk magnetization, (b) SQUID and neutron reflectivity (NR) measurements consistently show enhanced magnetization from bulk values, (c) NR data is fitted to obtain the uniform magnetic depth profile of CuCr2O4 films shown in (d).

2. Broader Impacts Yuri Suzuki, University of California-Berkeley, DMR 1104401 • High school spring internship program with local Oakland, CA high school in its ninth year • One week program including morning tutorials and training followed by afternoon hands-on sessions in the lab • High school curriculum development • Developing framework for science education at new high school on San Francisco Peninsula to begin fall 2013 • Developing an academic year internship program associated with year long course at local Oakland high school High school interns collaborating on magnetics project High school intern working on a vibrating sample magnetometer