1. Spin transport studies in band and interface tailored materials: towards total spin polarization for spin electronics Jagadeesh S. Moodera, Massachusetts Institute of Technology, DMR 0504158 Spin polarization across epitaxial Fe/MgO is > 70%, and that across EuS is > 80% Symmetry Filtering + Spin Filtering = Large TMR I. Goal here was investigation on spin filtering and symmetry filtering hybrid tunnel barrier by creating an optimum hybrid tunnel barrier to achieve a large tunnel magnetoresistance (TMR). This is achieved by - Symmetry filtering - the preferential tunneling of electrons with Δ 1 symmetry (spin up band) through epitaxial MgO tunnel barriers, known to yield extremely large spin polarization and TMR. - Spin filtering (selective tunneling of electrons from only one spin band) across europium chalcogenides can generate highly spin polarized tunnel currents. Our experimental results: Hybrid barrier was successful - TMR up to 44% Polarized neutron reflectivity (PNR) analysis (in collaboration with Dr. Julie Borchers at NIST) revealed roughened/intermixed interface II. Study of organic semiconductor/ferromagnet interface, investigated by PNR - weakening of interface magnetism was observed (first such study). Interface engineering and better understanding needed in both studies given above MBE grown thin film tunnel junction sample on (100)Si: MgO(50 Å )/Fe(200 Å )/MgO(20 Å )/EuS(30 Å )/Al(200 Å)/Au(50Å) Si (100) bcc-Fe Al poly-EuS epi-MgO (a) (b) Experimentally observed TMR at low temp. a) Plot shows TMR behavior under positive and negative bias voltages (b) The bias dependence of the TMR effect bias dependence shows nonmonotonic and asymmetric behavior

2. 3 high school students and 2 undergrads (one female and another under the REU program) participated in our summer research activity through Boston University Research Internship in Science & Engineering Program. They carried out independent experimental research projects on several current hot topics, based on which they gave oral as well as poster presentations open to the public 2009 Summer HS students have won national level competitions and have been admitted to MIT, Caltech, Cornell… 7 diploma or visiting students/scholars from abroad (France, Holland, Germany, Finland and China) have spent anywhere from three weeks to a year in our lab for their diploma thesis or as part of collaboration 10 research articles were published in the past year: 5 Phys. Rev B, 1 Euro Phys Lett, 3 Appl. Phys. Lett., 1 J. Appl. Phys. Other prominent publications include a feature article for Physics Today and a chapter for “Organic Spintronics” book. A review article for Annual Review of Condensed Matter Physics, is ready for publication 12 conference presentations and invited talks have resulted from the research work One Ph.D student graduated in this period has joined Intel Corp Three HS students and an undergrad during 2010 summer doing experimental research - an ongoing outreach program in PI’s Lab for the past 20+ years Doug Hutchings Nicholas Woodward, undergraduate intern seen in the background Evan Patel A postdoc helping Tyler in the background Tyler Kehne Nic seen in the background is helping Tyler Spin transport studies in band and interface tailored materials: towards total spin polarization for spin electronics Jagadeesh S. Moodera, Massachusetts Institute of Technology, DMR 0504158