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Yttrium Iron Garnet Nano Films: Epitaxial Growth, Spin Pumping Efficiency, and Pt Capping-Caused Damping

Event Details

Event Dates: 

Thursday, May 2, 2013 - 6:00am

Seminar Location: 

  • Duane Physics Room D142

Speaker Name(s): 

Mingzhong Wu

Speaker Affiliation(s): 

Seminar Type/Subject

Scientific Seminar Type: 

  • Condensed Matter Seminar

Event Details & Abstract: 

If a magnetic field is applied to a magnetic material, the field produces a torque on the magnetization of the material and drives it to precess.  This precession is similar to the motion of a spinning top where the gravitational field produces a torque, instead of the magnetic field.  It turns out that magnetization precession in yttrium iron garnet (YIG) decays slower than in any other known magnetic material.  This fact gives rise to the recent birth of a new paradigm in the discipline of spintronics – “spintronics using yttrium iron garnets”.  This talk will touch on several topics related to YIG spintronics.  The presentation consists of three main parts.  The first part will demonstrate the feasibility of the use of pulsed laser deposition techniques to grow low-damping nanometer-thick YIG films.  Low-damping YIG nano films are critically needed for both fundamental studies (such as the study of spin pumping) and device applications (such as spin torque oscillators).  Surface imperfection-associated damping in YIG nano films will also be discussed.  The second part will present the determination of efficiency of spin angular momentum transfer across YIG/normal metal interfaces and the demonstration of the use of YIG nano films to produce pure spin currents.  The last part will report damping enhancement in YIG nano films due to Pt capping layers.  The results reported in this part not only demonstrate a new type of damping in magnetic films, but are also of practical significance, as Pt is being widely used as spin-current sources and detectors.