Bulletin of the American Physical Society
2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009; Pittsburgh, Pennsylvania
Session L2: Buckley and Lilienfeld Prize |
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Sponsoring Units: DCMP Chair: Warren Pickett, University of California, Davis Room: Spirit of Pittsburgh Ballrom BC |
Tuesday, March 17, 2009 2:30PM - 3:06PM |
L2.00001: Oliver E. Buckley Prize Talk: Birth of tunnel magnetoresistance and its development Invited Speaker: Nowadays usually we use the word, tunnel magnetoresistance, but it required a long time to combine both words tunnel and magnetoresistance. The study of tunnel junction may originate p-n junction studied first around 1950. On the other hand, magnetoresistance effect was reported first in 1857 which was about 100 years earlier than the start of tunnel junction study. The research of tunnel magnetoresoistance has been mainly developed first for Al-oxide tunnel barrier junctions and made a big progress by the appearance of MgO barrier junctions for both basic research and applications. More recently Heusler electrode tunnel junctions exhibits a large TMR ratio up to about 750 {\%}. In my talk I will explain first the history of the study of tunnel junction and magnetoresistance effect. Then, I will focus on the Heusler electrode junctions and also application of tunnel magnetoresoistance junctions. [Preview Abstract] |
Tuesday, March 17, 2009 3:06PM - 3:42PM |
L2.00002: Oliver E. Buckly Prize Talk: Spin-dependent tunneling Invited Speaker: This abstract not available. [Preview Abstract] |
Tuesday, March 17, 2009 3:42PM - 4:18PM |
L2.00003: Oliver E. Buckley Prize Talk: Spin polarized tunneling and tunnel magnetoresistance -- Learning from the past and moving forward Invited Speaker: Electron tunneling phenomenon has contributed enormously to our understanding of various branches of physics over the years. The technique of spin polarized tunneling (SPT), sensing the spin polarization of tunneling electrons using a superconducting spin detector, discovered by Meservey and Tedrow in the early seventies has been successfully utilized over the years to understand many aspects of magnetism and superconductivity. Electrical spin injection/detection in a semiconductor is strongly believed to succeed through such an approach. The successful observation of a large change in tunnel current in magnetic tunnel junctions (MTJ) in the mid nineties has brought extreme activity in this field -- both from fundamental study as well as extensive application in mind (as sensors, nonvolatile memory devices, logic elements etc). From the early history of this field that led to the discovery of room temperature TMR effect to the observation of many novel phenomena to the exciting recent work on spin filtering, spin transport in semiconductors to toggling of the superconducting state with spin current will be highlighted and reviewed. Work done in collaboration with Drs. Meservey and Tedrow, PhD students, postdoctorals, as well as high school students and undergraduates. NSF, ONR, DARPA and KIST-MIT project funds supported the research over the years. [Preview Abstract] |
Tuesday, March 17, 2009 4:18PM - 4:54PM |
L2.00004: Oliver E. Buckley Prize Talk: Discovery and exploration of spin-dependent tunneling Invited Speaker: Experiments on thin-film superconductors in intense magnetic fields by R. Meservey and P. M. Tedrow led to the discovery of spin-polarized tunneling. Measurements of the critical magnetic of very thin aluminum films for temperatures down to 0.45K verified that spin-orbit scattering had to be included in the BCS description of the critical field. Theory predicted a first order transition at low temperature, and, although measurements of the shape of the resistive transition of the films strongly implied the existence of such a transition, magnetic field-dependent tunneling measurements of the energy gap of the aluminum were undertaken to observe directly the first-order nature of the transition. Splitting of the superconducting density of states by the applied magnetic field, i.e., spin-dependent tunneling, was observed in these measurements. Subsequent tunneling experiments demonstrated the spin polarization of tunnel currents from ferromagnets. The extension of these tunneling studies to include a wide range of superconductors and magnetic materials produced new qualitative and quantitative information about the behavior of conduction electron spins in such materials. Although experimental technique and theory have improved from these early times, there remain unanswered questions concerning electron tunneling into ferromagnets. An overview of these early experiments will be presented.\footnote{A review can be found in R. Meservey and P. M. Tedrow, Physics Reports \textbf{238}, 175 (1994).} [Preview Abstract] |
Tuesday, March 17, 2009 4:54PM - 5:30PM |
L2.00005: Julius Edgar Lilienfeld Prize: The RG and me: love at first bite Invited Speaker: From the time I took the first bite out of that cut-off, I have been in love with the Renormalization Group, returning to it over and over again to apply it to classical and quantum problems, in clean as well as disordered systems. This talk, aimed at non-experts, introduces and illustrates the RG ideas, with a favorite application, understanding Landau's Fermi liquid. [Preview Abstract] |
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