University of Minnesota
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Paul Crowell

Professor

PHYS 349 (office), 624-4828
PHYS S13 (lab), 626-9371
crowell @ physics.umn.edu

Crowellnew6web.jpg

Paul Crowell has been on the faculty of the University of Minnesota since 1997 and is currently a Professor of Physics.

McKnight Land Grant Professor, University of Minnesota 1999-2001, Sloan Foundation Fellow, 1999-2001, McKnight Presidential Fellow, University of Minnesota, 2004-2007, Fellow of the American Physical Society, 2008.

General Chair, Joint MMM/Intermag Conference; Chair-Elect of the APS Topical Group on Magnetism and its Applications (2011-2012); Organizer, Focus Session on Spin-Dependent Phenomena in Semiconductors, APS March Meeting, 2010; Program Committee, Conference on Magnetism and Magnetic Materials, 2005-2008, 2010; Program Committee Seventh International School of Spintronics and Quantum Information Technology, Japan (2011); Program Co-Chair, Conference on Magnetism and Magnetic Materials, Austin (2008);

Research Areas
Spin dynamics and transport in ferromagnets and ferromagnet-semiconductor heterostructures.

Current Research

My research focuses on spin dynamics and transport in ferromagnets and ferromagnet-semiconductor heterostructures. The first project, funded by NSF, examines the role of non-equilibrium effects in spin transport in hybrid ferromagnet/semiconductor structures. The materials development for this work is carried out in collaboration with Chris Palmstrom's group at UCSB, who is a collaborator in the University of Minnesota MRSEC. In recent years, we have succeeded in fabricating simple devices that can be used to test theories of spin transport across interfaces as well as of spin dynamics in the presence of spin-orbit and hyperfine interactions. Similar questions, particularly about the role of interfaces, appear in studies of spin transport in all-metallic heterostructures, a research project that is being carried out in collaboration with Professor Chris Leighton through the MRSEC. A third topic of interest is magnetization dynamics, both in domain structures such as vortices as well as in spintronic devices. In collaboration with Leighton, we are looking at the impact of physical microstructure on vortex dynamics. In a newer collaboration with Professor Jianping Wang (ECE), we are investigating the dynamics in MgO-based spin transfer torque devices.

Advisees and Collaborators

Kevin Christie, Research Assistant
Michael Erickson, Research Assistant
Andrew Galkiewicz, Research Assistant
Chad Geppert, Research Assistant
Changjiang Liu, Teaching Assistant
Timothy Peterson, Research Assistant
Dmitry Spivak, Research Assistant
Gordon Stecklein, Research Assistant
Justin Watts, Teaching Assistant

Selected Publications

T.Y. Chen, A.T. Galkiewicz, and P.A. Crowell, Phase Diagram of Magnetic Vortex Dynamics, Physical Review B 180406(R) (2012)

Y. Zhang, H. Zhao, A. Lyle, P.A. Crowell, and J.P. Wang, High power and low critical current spin torque oscillation from a magnetic tunnel junction with a built-in hard axis polarizer, Applied Physics Letters 100, 032405 (2012)

T. Y. Chen, M. J. Erickson, P. A. Crowell, and C. Leighton, Surface Roughness Dominated Pinning Mechanism of Magnetic Vortices in Soft Ferromagnetic Films, Phys. Rev. Lett. 109, 097202 (2012) [download Chen_Submitted.pdf]

Q. O. Hu, E. S. Garlid, P. A. Crowell, and C. J. Palmstrom, Spin accumulation near Fe/GaAs(001) interfaces: The role of semiconductor band structure, Physical Review B, 84 085306 (2011)

P. A. Crowell and S. A. Crooker, Spin Transport in Ferromagnet/III-V Semiconductor Heterostructures, Handbook of Spin Transport and Magnetism, edited by E.Y. Tsymbal and I. Zutic (2011) [download Crowell_Chapter23.pdf]

Y. S. Zhang, H. Zhao, A. Lyle, P. A. Crowell, and J. P. Wang, Spin torque oscillation modes of a dual magnetic tunneling junction, Journal of Applied Physics 109, 07D307 (2011)

E. S. Garlid, Q. O. Hu, M. K. Chan, C. J. Palmstrøm, and P. A. Crowell , Electrical Measurement of the Direct Spin Hall Effect in Fe/InxGa1-xAs Heterostructures, Physical Review Letters 105, 156602 (2010)

T.Y. Chen and P.A. Crowell, Non-linear dynamics of a magnetic vortex, IEEE Transactions on Magnetics 46, 1457 (2010)

R.L. Compton, T.Y. Chen, and P.A. Crowell, Magnetic vortex dynamics in the presence of pinning, Physical Review B 81 144412 (2010)

B. D. Schultz, N. Marom, D. Naveh, X. Lou, C. Adelmann, J. Strand, P. A. Crowell, L. Kronik, and C. J. Palmstrøm , Spin injection across the Fe/GaAs interface: Role of interfacial ordering, Phys. Rev. B 80, 201309 (2009) [abstract]

M. K. Chan, Q. O. Hu, J. Zhang, T. Kondo, C. J. Palmstrøm, and P. A. Crowell , Hyperfine interactions and spin transport in ferromagnet-semiconductor heterostructures, Phys. Rev. B 80, 161206(R)(2009) [abstract]

S. A. Crooker, E. S. Garlid, A. N. Chantis, D. L. Smith, K. S. M. Reddy, Q. O. Hu, T. Kondo, C. J. Palmstrøm, and P. A. Crowell, Bias-controlled sensitivity of ferromagnet/semiconductor electrical spin detectors, Physical Review B 80 041305(R) (2009) [abstract]

X. Lou, C. Adelmann, S. A. Crooker, E. S. Garlid, J. Zhang, S. M. Reddy, S. D. Flexner, C. J. Palmstrøm, and P. A. Crowell, Electrical Detection of Spin Transport in Lateral Ferromagnet-Semiconductor Devices, Nature Physics 3, 197 (2007)

R. L. Compton and P. A. Crowell, Dynamics of a Pinned Magnetic Vortex, Phys. Rev. Lett. 97, 137202 (2006)

C. Adelmann, J. L. Hilton, B. D. Schultz, S. McKernan, C. J. Palmstrøm, X. Lou, H.-S. Chiang, and P. A. Crowell, Spin Injection from Perpendicular Magnetized Ferromagnetic δ-MnGa into (Al,Ga)As Heterostructures, Appl. Phys. Lett. 89, 112511 (2006)

X. Lou, C. Adelmann, M. Furis, S. A. Crooker, C. J. Palmstrøm, and P. A. Crowell, Electrical Detection of Spin Accumulation at a Ferromagnet-Semiconductor Interface, Phys. Rev. Lett. 96, 176603 (2006).

J. Strand, X. Lou, C. Adelmann, B. D. Schultz, A. F. Isakovic, C. J. Palmstrøm, and P. A. Crowell, Electron Spin Dynamics and Hyperfine Interactions in Fe/Al0.1Ga0.9As/GaAs Spin Injection Heterostructures, Phys. Rev. B 72, 155308 (2005).

J. P. Park and P. A. Crowell, Interactions of Spin Waves with a Magnetic Vortex, Phys. Rev. Lett. 95, 167201 (2005)

S. A. Crooker, M. Furis, X. Lou, C. Adelmann, D. L. Smith, C. J. Palmstrøm, and P. A. Crowell, Imaging spin injection and accumulation in lateral ferromagnet/semiconductor devices, Science 309, 2191(2005)

C. Adelmann, X. Lou, J. Strand, C. J. Palmstrøm, and P. A. Crowell, Spin Injection and Relaxation in Ferromagnet-Semiconductor Heterostructures, Phys. Rev. B 71 121301(R) (2005).

C. Bayer, J. P. Park, H. Wang, M. Yan, C. E. Campbell, and P. A. Crowell, Spin Waves in an Inhomogeneously Magnetized Stripe, Phys. Rev. B 69, 134401 (2004)

M. K. Chan, J. S. Parker, P. A. Crowell, and C. Leighton, “Identification and Separation of Two Distinct Contributions to the Training Effect in Polycrystalline Exchange Biased Co/FeMn Bilayers,”, Phys. Rev. B (2008)

M.R. Fitzsimmons, B.J. Kirby, N.W. Hengartner, F. Trouw, M.J. Erickson, S.D. Flexner, T. Kondo, C. Adelmann, C.J. Palmstrøm, P.A. Crowell, W.C. Chen, T.R. Gentile, J.A. Borchers, C.F. Majkrzak, and R. Pynn , “Suppression of Nuclear Polarization near the Surface of Optically Pumped GaAs,”, Phys. Rev. B. (2007)

M. K. Chan, J. S. Parker, P. A. Crowell, and C. Leighton, “Identification and Separation of Two Distinct Contributions to the Training Effect in Polycrystalline Exchange Biased Co/FeMn Bilayers,”, Phys. Rev. B (2008)

M. K. Chan, J. S. Parker, P. A. Crowell, and C. Leighton,, “Identification and Separation of Two Distinct Contributions to the Training Effect in Polycrystalline Exchange Biased Co/FeMn Bilayers,”, Phys. Rev. B (2008)

J. Strand, A. F. Isakovic, X. Lou, P. A. Crowell, B. D. Schultz, and C. J. Palmstrom, Nuclear Magnetic Resonance in a Ferromagnet-Semiconductor Heterostructure, Appl. Phys. Lett. 83, 3335 (2003)

J. Strand, B. D. Schultz, A. F. Isakovic, C. J. Palmstrom, and P. A. Crowell, Dynamical Nuclear Polarization by Electrical Spin Injection in Ferromagnet-Semiconductor Heterostructures, Phys. Rev. Lett. 91, 036602 (2003)

J. P. Park, P. Eames, D. M. Engebretson, J. Berezovsky, and P. A. Crowell, Spatially Resolved Dynamics of Localized Spin-Wave Modes in Ferromagnetic Wires, Phys. Rev. Lett. 89, 277201 (2002)

J. P. Park, P. Eames, D. M. Engebretson, J. Berezovsky, and P. A. Crowell, Imaging of Spin Dynamics in Closure Domain and Vortex Structures, Phys. Rev. B 67, 020403R (2003)

J. N. Heyman, H. Wrage, C. Lind, D .Hebert, P. Neocleous, P. A. Crowell, T. Muller, and K. Unterrainer, Terahertz Emission from Magneto-plasma Oscillations in Semiconductors, Proceedings of SPIE, accepted for publication (2002).

M. Yan, J. Berezovsky, P. A. Crowell, and C. E. Campbell, Simulations of Magnetic Dynamics in Iron-Cobalt Films, Condensed Matter Theories Vol 17, edited by M. P. Das and F. Green (Nova, New York, 2003, p. 295.

D. M. Engebretson, J. Berezovsky, J. P. Park, L. C. Chen, C. J. Palmstrom, and P. A. Crowell, Time-Domain Ferromagnetic Resonance in Epitaxial Thin Films, J. Appl. Phys. 91, 8040 (2002)

A. F. Isakovic, D. M. Carr, J. Strand, B. D Schultz, C. J. Palmstrom, and P. A. Crowell, Optically Pumped Transport in Ferromagnet-Semiconductor Schottky Diodes, J. Appl. Phys. 91, 7261 (2002)

A. F. Isakovic, D. M. Carr, J. Strand, B. D. Schultz, C. J. Palmstrom, and P.A. Crowell, Optical Pumping in Ferromagnet-Semiconductor Heterostructures: Magneto-optics and Spin Transport, Phys. Rev. B 64, 161304R (2001)

J. N. Heyman, P. Neocleous, D. Hebert, P. A. Crowell, T. Muller, and K. Unterrainer, Terahertz Emission from GaAs and InAs in a Magnetic Field, Phys. Rev. B 64, 085202 (2001)

A. F. Isakovic, J. Berezovsky, P. A. Crowell, L. C. Chen, D. M. Carr, B. D. Schultz, and C. J. Palmstrom, Control of Magnetic Anisotropy in Fe1-xCox Films on Vicinal GaAs and Sc1-yEryAs Surfaces, Journal of Applied Physics 89, 6674 (2001)

M. Veum, C. Pettersen, P. Mach, P. A. Crowell, and C. C. Huang, Temperature Variation of Film Tension Measured by a Vibrating Membrame Tensiometer, Phys. Rev. E. 61, R2192 (2000)

L. C. Chen, J. W. Dong, B. D. Schultz, C. J. Palmstrom, J. Berezovsky, A. Isakovic, P. A. Crowell, and N. Tabat, Epitaxial Ferromagnetic Metal/GaAs (001) Heterostructures, J. Vac. Sci. Tech. B 18, 2057 (2000)

B. Beschoten, P. A. Crowell, I. Malajovich, D. D. Awschalom, F. Matsukura, A. Shen, and H. Ohno, Magnetic Circular Dichroism Studies of Carrier-Induced Ferromagnetism in (Ga1-xMnx)As, Phys. Rev. Lett. 83, 3073 (1999)

P. A. Crowell, V. Nikitin, J. A. Gupta, D. D. Awschalom, F. Flack and N. Samarth, Optical Spectroscopy of II-VI (Magnetic) Semiconductor Quantum Dots, Physica E 2, 854 (1998)

P. A. Crowell, D. K. Young, S. Keller, E. L. Hu, and D. D. Awschalom, Near-field scanning optical spectroscopy of an InGaN quantum well, Appl. Phys. Lett. 72, 927 (1998)

V. Nikitin, P. A. Crowell, J. A. Gupta, D. D. Awschalom, F. Flack, and N. Samarth, Zero-dimensional excitonic confinement in locally strained Zn[sub 1 - x]Cd[sub x]Se quantum wells, Appl. Phys. Lett. 71, 1213 (1997).

Education

Ph.D., Cornell University, 1994
1986,Cornell University, 1989
B.A., Swarthmore College, 1986