Dr Steven Clowes
EPSRC Advanced Research Fellow
Qualifications: MSc, PhD
Email: s.clowes@surrey.ac.uk
Phone: Work: 01483 68 9827
Room no: 12 ATI 02
Further information
Biography
1994 BSc in Physics from University of York, UK
1995 MSc in Surface Science from Loughborough University, UK
1999 PhD in Experimental Studies of Surface-Adsorbate Interactions and Surface magnetism from University of York, UK
1999-2001 postdoctoral research associate at Rutgers University NJ, USA
2001-2007 postdoctoral research associate at Imperial College London, UK
2007 Laboratory Manager of fabrication facilities for the ATI
2007 EPSRC Advanced Research Fellow at the ATI
Research Interests
Semiconductor spintronics
Research Collaborations
Imperial College London
Cambridge University
Publications
Highlights
- .
(2012) 'Observation of spin dependent photocoductivity in InSb quantum well nanowires'. AIP Applied Physics Letters, 101 (15)doi: 10.1063/1.4760223Full text is available at: http://epubs.surrey.ac.uk/735787/
Abstract
We report on the electrical detection of spin dependent photoconductivity in 500 nm wide InSb quantum well nanowires using the optical orientation of electron spins. By applying weak magnetic fields (≈ 200 mT), we observe a spin filtering effect of classical origin caused by spin dependent back scattering of electrons from the sidewalls. Spin dependent features in the longitudinal photovoltage decay with temperature and disappears at characteristic energy (≈ 50 K) consistent with the theoretical spin splitting and the thermal level broadening. We show that the observed signal is due to the inversion asymmetry of the quantum well, with an additional Zeeman contribution. © 2012 American Institute of Physics.
- . (2012) 'Temperature dependent optical properties of PbS nanocrystals.'. Nanotechnology, England: 23 (27)
- .
(2012) 'Transverse focusing of spin-polarized photocurrents'. American Physical Society Physical Review B (Condensed Matter and Materials Physics), 85 Article number 045431 Full text is available at: http://epubs.surrey.ac.uk/148877/
Abstract
We measure transverse magnetically focused photocurrent signals in an InSb/InAlSb quantum well device. Using optical spin orientation by modulated circularly polarized light an electron spin-dependent signal is observed due to the spin-orbit interaction. Simulations of the focusing signal are performed using a classical billiard ball model, which includes both spin precession and a spin-dependent electron energy. The simulated data suggest that a signal dependent on the helicity of the incident light is expected for a Rashba parameter α > 0.1 eVÅ and that a splitting of the focusing signal is not expected to be observed in linear polarized photocurrent and purely electrical measurements.
- .
(2012) 'Interplay of spin and orbital magnetogyrotropic photogalvanic effects in InSb/(Al,In) Sb quantum well structures'. PHYSICAL REVIEW B, 85 (4) Article number ARTN 045305 Full text is available at: http://epubs.surrey.ac.uk/56945/
- .
(2011) 'Experimental determination of the Rashba coefficient in InSb/InAlSb quantum wells at zero magnetic field and elevated temperatures'. IOP PUBLISHING LTD JOURNAL OF PHYSICS-CONDENSED MATTER, 23 (3) Article number ARTN 035801 Full text is available at: http://epubs.surrey.ac.uk/7763/
- .
(2010) 'Strong dependence of spin dynamics on the orientation of an external magnetic field for InSb and InAs'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 96 (11) Article number ARTN 111107 doi: 10.1063/1.3337111Full text is available at: http://epubs.surrey.ac.uk/7724/
- .
(2007) 'Electrical characterization of MgO tunnel barriers grown on InAs (001) epilayers'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 91 (12) Article number ARTN 122106 doi: 10.1063/1.2784933Full text is available at: http://epubs.surrey.ac.uk/470/
- . (2007) 'Oblique Hanle measurements of InAs/GaAs quantum dot spin-light emitting diodes'. AMER INST PHYSICS Physics of Semiconductors, Pts A and B, Vienna, AUSTRIA: 28th International Conference on the Physics of Semiconductors (ICPS-28) 893, pp. 1289-1290.
- .
(2006) 'Oblique Hanle measurements of InAs/GaAs quantum dot spin-light emitting diodes'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 88 (2) Article number ARTN 022113 doi: 10.1063/1.2163074Full text is available at: http://epubs.surrey.ac.uk/350/
Journal articles
- .
(2012) 'Observation of spin dependent photocoductivity in InSb quantum well nanowires'. AIP Applied Physics Letters, 101 (15)doi: 10.1063/1.4760223Full text is available at: http://epubs.surrey.ac.uk/735787/
Abstract
We report on the electrical detection of spin dependent photoconductivity in 500 nm wide InSb quantum well nanowires using the optical orientation of electron spins. By applying weak magnetic fields (≈ 200 mT), we observe a spin filtering effect of classical origin caused by spin dependent back scattering of electrons from the sidewalls. Spin dependent features in the longitudinal photovoltage decay with temperature and disappears at characteristic energy (≈ 50 K) consistent with the theoretical spin splitting and the thermal level broadening. We show that the observed signal is due to the inversion asymmetry of the quantum well, with an additional Zeeman contribution. © 2012 American Institute of Physics.
- . (2012) 'Temperature dependent optical properties of PbS nanocrystals.'. Nanotechnology, England: 23 (27)
- .
(2012) 'Transverse focusing of spin-polarized photocurrents'. American Physical Society Physical Review B (Condensed Matter and Materials Physics), 85 Article number 045431 Full text is available at: http://epubs.surrey.ac.uk/148877/
Abstract
We measure transverse magnetically focused photocurrent signals in an InSb/InAlSb quantum well device. Using optical spin orientation by modulated circularly polarized light an electron spin-dependent signal is observed due to the spin-orbit interaction. Simulations of the focusing signal are performed using a classical billiard ball model, which includes both spin precession and a spin-dependent electron energy. The simulated data suggest that a signal dependent on the helicity of the incident light is expected for a Rashba parameter α > 0.1 eVÅ and that a splitting of the focusing signal is not expected to be observed in linear polarized photocurrent and purely electrical measurements.
- .
(2012) 'Interplay of spin and orbital magnetogyrotropic photogalvanic effects in InSb/(Al,In) Sb quantum well structures'. PHYSICAL REVIEW B, 85 (4) Article number ARTN 045305 Full text is available at: http://epubs.surrey.ac.uk/56945/
- . (2011) 'Sophisticated test objects for the quality assurance of optical computed tomography scanners.'. Phys Med Biol, England: 56 (14), pp. 4177-4199.
- .
(2011) 'Experimental determination of the Rashba coefficient in InSb/InAlSb quantum wells at zero magnetic field and elevated temperatures'. IOP PUBLISHING LTD JOURNAL OF PHYSICS-CONDENSED MATTER, 23 (3) Article number ARTN 035801 Full text is available at: http://epubs.surrey.ac.uk/7763/
- .
(2010) 'Strong dependence of spin dynamics on the orientation of an external magnetic field for InSb and InAs'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 96 (11) Article number ARTN 111107 doi: 10.1063/1.3337111Full text is available at: http://epubs.surrey.ac.uk/7724/
- .
(2008) 'Interface properties of Pb/InAs planar structures for Andreev spectroscopy'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 92 (1) Article number ARTN 012501 doi: 10.1063/1.2828979Full text is available at: http://epubs.surrey.ac.uk/378/
- .
(2007) 'Electrical characterization of MgO tunnel barriers grown on InAs (001) epilayers'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 91 (12) Article number ARTN 122106 doi: 10.1063/1.2784933Full text is available at: http://epubs.surrey.ac.uk/470/
- . (2007) 'Preparation of InAs(001) surface for spin injection via a chemical route'. IOP PUBLISHING LTD JOURNAL OF PHYSICS D-APPLIED PHYSICS, 40 (10), pp. 3190-3193.
- .
(2007) 'Temperature insensitivity of the spin-polarization in Co2MnSi films on GaAs (001)'. IOP PUBLISHING LTD NEW JOURNAL OF PHYSICS, 9 Article number PII S1367-2630(07)34448-0 Full text is available at: http://epubs.surrey.ac.uk/124/
- . (2006) 'Exploration of the inherent magnetoresistance in InSb thin films'. IOP PUBLISHING LTD SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 21 (12), pp. 1543-1546.
- . (2006) 'Spin relaxation in n-InSb/AlInSb quantum wells'. IOP PUBLISHING LTD NEW JOURNAL OF PHYSICS, 8 Article number PII S1367-2630(06)15617-7
- .
(2006) 'Oblique Hanle measurements of InAs/GaAs quantum dot spin-light emitting diodes'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 88 (2) Article number ARTN 022113 doi: 10.1063/1.2163074Full text is available at: http://epubs.surrey.ac.uk/350/
- .
(2006) 'Tuning the inherent magnetoresistance of InSb thin films'. AMER INST PHYSICS APPLIED PHYSICS LETTERS, 88 (1) Article number ARTN 012110 doi: 10.1063/1.2162666Full text is available at: http://epubs.surrey.ac.uk/454/
- . (2005) 'Evidence for dislocation-related amphoteric behaviour of Si dopant in high-mobility InSb thin films'. IOP PUBLISHING LTD SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 20 (12), pp. 1153-1156.
Conference papers
- .
(2011) 'Substantial temperature dependence of transverse electron g*-factor in lead chalcogenide multi-quantum wells'. American Institute of Physics AIP Conference Proceedings, Blacksburg, USA: 15TH INTERNATIONAL CONFERENCE ON NARROW GAP SYSTEMS 1416, pp. 178-180.doi: 10.1063/1.3671728
- .
(2011) 'Manipulation of spin dynamics in semiconductor structures by orientation of small external magnetic field'. American Institute of Physics AIP Conference Proceedings, Seoul, South Korea: ICPS2010, 30th International Conference on the Physics of Semiconductors 1399, pp. 657-658.doi: 10.1063/1.3666548
- . (2010) 'Carbon nanotube field effect transistor measurements in vacuum'. IEEE International Conference on Semiconductor Electronics, Proceedings, ICSE, , pp. 224-228.
- . (2008) 'Gate dependence of spin-splitting in an InSb/InAlSb quantum well'. SPRINGER NARROW GAP SEMICONDUCTORS 2007, Guildford, ENGLAND: 13th International Conference on Narrow Gap Semiconductors 119, pp. 3-5.
- . (2008) 'Density and well-width dependence of the spin relaxation in n-InSb/AlInSb quantum wells'. SPRINGER NARROW GAP SEMICONDUCTORS 2007, Guildford, ENGLAND: 13th International Conference on Narrow Gap Semiconductors 119, pp. 19-21.
- . (2008) '(S)TEM Characterisation of InAs/MgO/Co Multilayers'. SPRINGER-VERLAG BERLIN MICROSCOPY OF SEMICONDUCTING MATERIALS 2007, Univ Cambridge, Cambridge, ENGLAND: 15th Conference on Microscopy of Semiconducting Materials 120, pp. 153-156.
- . (2007) 'Planar Andreev spectroscopy in InAs'. AMER INST PHYSICS Physics of Semiconductors, Pts A and B, Vienna, AUSTRIA: 28th International Conference on the Physics of Semiconductors (ICPS-28) 893, pp. 1281-1282.
- . (2007) 'Oblique Hanle measurements of InAs/GaAs quantum dot spin-light emitting diodes'. AMER INST PHYSICS Physics of Semiconductors, Pts A and B, Vienna, AUSTRIA: 28th International Conference on the Physics of Semiconductors (ICPS-28) 893, pp. 1289-1290.
- . (2007) 'Inherent magnetoresistance and surface morphology of InSb thin films'. AMER INST PHYSICS Physics of Semiconductors, Pts A and B, Vienna, AUSTRIA: 28th International Conference on the Physics of Semiconductors (ICPS-28) 893, pp. 561-562.
- . (2007) 'Improved geometric control of the high-field linear magnetoresistance by metallic bridges in InSb arrays'. AMER INST PHYSICS Physics of Semiconductors, Pts A and B, Vienna, AUSTRIA: 28th International Conference on the Physics of Semiconductors (ICPS-28) 893, pp. 1383-1384.
Books
- . (2008) Narrow gap semiconductors 2007. Springer
Teaching
Level 2 Modern Physics / Atomic Physics component
Second year laboratory
Departmental Duties
Academic in charge of cleanroom facilities.

