S. James Allen, received a Ph.D. degree in electrical engineering from M.I.T. in 1965.  He was appointed Professor of  Physics and Director of the Quantum Institute at UCSB in 1991, and recently served as Chair of Physics, 2000-05. In 2009 he became emeritus and was appointed Research Professor of Physics.   Prior to that, he had been a member of technical staff at Bell Labs, where he was recognized as a “Distinguished Member of Technical Staff”,  had availed himself of a Bell Labs supported leave at the Royal School of Mines , Imperial College London and later joined Bellcore, as District Research Manager of Solid State Physics Research.  He has also been an adjunct professor at Northeastern University and at Princeton University.   Professional service has included election as Member at Large of the Executive Committee of the Division of Condensed Matter Physics of the A.P.S. where he served on the Strategic Planning Committee and on the Nominating Committee.  He has also served on the Editorial Board of Physical Review.  In 1995 he won a Humboldt Science Award, is a Fellow of the American Physical Society and a Fellow of the American Association for the Advancement of Science.

 He has co-authored more than 200 publications on transport and terahertz excitations in semiconductor nano-structures, hot-electron dynamics, high temperature superconductivity, magnetism, superionic conductors, metal physics, clathrate inclusion compounds,protein dynamics and complex oxide heterostructures. He holds three patents.  Current research focuses on terahertz dynamics in semiconductor quantum structures far from equilibrium, novel plasmonic terahertz detectors, spin wave logic devices, terahertz dynamics of bio-polymers in solution and 2D Mott systems in complex oxide heterostructures.

Current Research Efforts

Emergent phenomena at Mott interfaces

Optical conductivity of 2-D Mott systems at oxide heterostructures

Spin wave logic devices:                

All spin logic devices based on spin waves in ferromagnetic films patterned as interferometers, local magnetization controlled switching and scattering from spin torque devices.

Plasmonic terahertz detectors:         

Voltage tuned plasmon resonances are exploited for narrow band terahertz detectors and are developed for terahertz spectroscopic focal plane arrays.

Terahertz biopolymer dynamics:     

Measuring the terahertz dynamics of proteins in solution by direct absorption spectroscopy and optical/terahertz sum and difference frequency generation in proteins in solution.

Recent Publications

Emergent phenomena at Mott interfaces

T. A. Cain, S. Lee, P. Moetakef, L. Balents, S. Stemmer, and S. J. Allen, "Seebeck coefficient of a quantum confined, high-electron-density electron gas in SrTiO3," Applied Physics Letters 100 (16), 161601 (2012).

J. Son, S. Rajan, S. Stemmer, and S. J. Allen, "A heterojunction modulation-doped Mott transistor," Journal of Applied Physics 110 (8) (2011).

J. Son, B. Jalan, A. P. Kajdos, L. Balents, S. J. Allen, and S. Stemmer, "Probing the metal-insulator transition of NdNiO3 by electrostatic doping," Applied Physics Letters 99 (19) (2011).

P. Moetakef, J. Y. Zhang, A. Kozhanov, B. Jalan, R. Seshadri, S. J. Allen, and S. Stemmer, "Transport in ferromagnetic GdTiO3/SrTiO3 heterostructures," Applied Physics Letters 98 (11), 112110 (2011).

P. Moetakef, T. A. Cain, D. G. Ouellette, J. Y. Zhang, D. O. Klenov, A. Janotti, C. G. Van de Walle, S. Rajan, S. J. Allen, and S. Stemmer, "Electrostatic carrier doping of GdTiO3/SrTiO3 interfaces," Applied Physics Letters 99 (23), 232116 (2011).

B. Jalan, S. J. Allen, G. E. Beltz, P. Moetakef, and S. Stemmer, "Enhancing the electron mobility of SrTiO3 with strain," Applied Physics Letters 98 (13), 132102 (2011).

J. Son, P. Moetakef, J. M. LeBeau, D. Ouellette, L. Balents, S. J. Allen, and S. Stemmer, "Low-dimensional Mott material: Transport in ultrathin epitaxial LaNiO3 films," Applied Physics Letters 96 (6), 062114 (2010).

J. Son, J. M. LeBeau, S. J. Allen, and S. Stemmer, "Conductivity enhancement of ultrathin LaNiO3 films in superlattices," Applied Physics Letters 97 (20), 202109 (2010).

D. G. Ouellette, S. Lee, J. Son, S. Stemmer, L. Balents, A. J. Millis, and S. J. Allen, "Optical conductivity of LaNiO3: Coherent transport and correlation driven mass enhancement," Physical Review B 82 (16), 165112 (2010).

B. Jalan, S. Stemmer, S. Mack, and S. J. Allen, "Two-dimensional electron gas in delta-doped SrTiO3," Physical Review B 82 (8), 081103 (2010).

Spin wave logic devices

A. Kozhanov, M. Popov, I. Zavislyak, D. Ouellette, D. W. Lee, S. X. Wang, M. Rodwell, and S. J. Allen, "Spin wave modes in ferromagnetic tubes," Journal of Applied Physics 111 (1), 013905 (2012).

A. Kozhanov, D. Ouellette, M. Rodwell, S. J. Allen, D. W. Lee, and S. X. Wang, "Micro-structured ferromagnetic tubes for spin wave excitation," Journal of Applied Physics 109 (7), 07d333 (2011).

A. Kozhanov, D. Ouellette, M. Rodwell, D. W. Lee, S. X. Wang, and S. J. Allen, "Magnetostatic Spin-Wave Modes in Ferromagnetic Tube," IEEE Transactions on Magnetics 45 (10), 4223-4225 (2009).

A. Kozhanov, D. Ouellette, M. Rodwell, S. J. Allen, A. P. Jacob, D. W. Lee, and S. X. Wang, "Dispersion and spin wave "tunneling" in nanostructured magnetostatic spin waveguides," Journal of Applied Physics 105 (7), 07d311 (2009).

A. Kozhanov, D. Ouellette, Z. Griffith, M. Rodwell, A. P. Jacob, D. W. Lee, S. X. Wang, and S. J. Allen, "Dispersion in magnetostatic CoTaZr spin waveguides," Applied Physics Letters 94 (1), 012505 (2009).

Plasmonic terahertz detectors

G. C. Dyer, S. Preu, G. R. Aizin, J. Mikalopas, A. D. Grine, J. L. Reno, J. M. Hensley, N. Q. Vinh, A. C. Gossard, M. S. Sherwin, S. J. Allen, and E. A. Shaner, "Enhanced performance of resonant sub-terahertz detection in a plasmonic cavity," Applied Physics Letters 100 (8), 083506 (2012).

G. C. Dyer, G. R. Aizin, J. L. Reno, E. A. Shaner, and S. J. Allen, "Novel Tunable Millimeter-Wave Grating-Gated Plasmonic Detectors," IEEE Journal of Selected Topics in Quantum Electronics 17 (1), 85-91 (2011).

G. C. Dyer, N. Q. Vinh, S. J. Allen, G. R. Aizin, J. Mikalopas, J. L. Reno, and E. A. Shaner, "A terahertz plasmon cavity detector," Applied Physics Letters 97 (19), 193507 (2010).

G. C. Dyer, J. D. Crossno, G. R. Aizin, E. A. Shaner, M. C. Wanke, J. L. Reno, and S. J. Allen, "A plasmonic terahertz detector with a monolithic hot electron bolometer," Journal of Physics-Condensed Matter 21 (19), 195803 (2009).

Terahertz biopolymer dynamics

N. Q. Vinh, S. J. Allen, and K. W. Plaxco, "Dielectric Spectroscopy of Proteins as a Quantitative Experimental Test of Computational Models of Their Low-Frequency Harmonic Motions," Journal of the American Chemical Society 133 (23), 8942-8947 (2011).

J. Xu, K. W. Plaxco, S. J. Allen, J. E. Bjarnason, and E. R. Brown, "0.15-3.72 THz absorption of aqueous salts and saline solutions," Applied Physics Letters 90 (3), 031908 (2007).

J. Xu, K. W. Plaxco, and S. J. Allen, "Absorption spectra of liquid water and aqueous buffers between 0.3 and 3.72 THz," Journal of Chemical Physics 124 (3), 036101 (2006).

J. Xu, K. W. Plaxco, and S. J. Allen, "Probing the collective vibrational dynamics of a protein in liquid water by terahertz absorption spectroscopy," Protein Science 15 (5), 1175-1181 (2006).

J. Xu, K. W. Plaxco, and S. J. Allen, "Collective dynamics of lysozyme in water: Terahertz absorption spectroscopy and comparison with theory," Journal of Physical Chemistry B 110 (47), 24255-24259 (2006).