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Bryan Gallagher

Professor of Physics, Faculty of Science

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Biography

1981 - 1984: Research Fellow, Department of Physics, University of Leeds, UK.

1984 - 1985: Research Associate, Cavendish Laboratories, University of Cambridge, UK.

1985 - 1996: Lecturer, Department of Physics, University of Nottingham, UK.

1996 - 2000: Senior Lecturer, School of Physics and Astronomy, University of Nottingham.

2000 - 2001: Royal Society Leverhulme Trust Senior Research Fellow

2000 - 2004: Reader, School of Physics and Astronomy, University of Nottingham, UK.

2004 - : Professor, School of Physics and Astronomy, University of Nottingham, UK.

Expertise Summary

I have worked very extensively for the last 10 year on ferromagnetic semiconductors. I have carried out important work elucidating the electronic and magnetic properties of ferromagnetic semiconductors including demonstrating the key role of Mn interstitial impurities, and achieving world record Curie temperatures. These achievements were reported in a series of papers[1],[2],[3],[4] which have already had a very large impact. These investigations have shed new light on single domain magnetic anisotropies[5],[6],[7],[8] and anisotropic magnetoresistance[9] leading to the discovery of several new phenomena, including Coulomb blockade anisotropic magnetoresistance[10],[11], and to patents and potential device applications.

My earlier research work was on the electrical transport properties of metals; particularly amorphous metals, alloys and transition metals. My contributions to this field are summarised in a Physics Reports review monograph[12].

For the last 25 years I have worked mostly on semiconductors. This initially involved low dimensional electron systems realised III-V semiconductor heterostructures fabricated by Molecular Beam Epitaxy (MBE) and subsequently processed by optical and electron beam lithography. Much of the work has involved nanostructured devices. I have worked extensively with cryogenic systems down to 10mK and high magnetic fields up to 70 Tesla.

I worked for many years on the Integer Quantum Hall effect (IQHE). My work on IQHE resistance standards, in collaboration with the National Physical Laboratory, led to the highest precision measurement of quantum Hall resistance ever achieved at the time[13]. I also carried out extensive work on the Fractional Quantum Hall effect, Wigner crystallization and 2D bi-layers in 2D hole devices. I was involved in the development of MBE grown p-type 2D devices with world record hole mobility[14] . Much of my work has focused on new quantum effects in electrical transport including studies of mesoscopic devices and ballistic transport. A major achievement of this period was the demonstration in mesoscopic conductors of a new phenomenon; Universal Thermopower Fluctuations[15], which are closely related to Universal Conductance Fluctuations.

I am an expert on thermoelectric effects and much of my early career involved experimental studies of thermoelectric effects in metals and semiconductors. I and wrote the chapter on thermoelectric effects in low dimensional and mesoscopic semiconductors in the definitive work Handbook on Semiconductors[16] , Vol. 1 p721-816 (1992) with Prof. P N Butcher.

I have also carried out extensive work on demonstrating the existence of, and potential for, nano-magnetometry[17], and novel magnetoresistance effects[18] in hybrid ferromagnet/ semiconductor devices.

[1] Applied Physics Letters 81, 16, 3010 (2002)

[2] Applied Physics Letters 81, 26, 4991 (2002)

[3] Physical Review Letters, 92 037201 (2004)

[4] Physical Review B 72 165204 (2005)

[5] Physical Review B (Rapid) 71, 121302 (2005)

[6] Physical Review Letters: 96 117207 (2006))

[7] Physical Review Letters, 95, 217204 (2005)

[8] Physical Review Letters, 100, 047202 (2008)

[9] Physical Review Letters 99, 147207 (2007)

[10] Physical Review Letters 94, 127202 (2005)

[11] Physical Review Letters: 97, 077201 (2006)

[12] Physics Reports 170, 265-324 (1992)

[13] Physical Review Letters 66, 969 (1991)

[14] Applied Physics Letters 65, 16, 2054 (1994).

[15] Physical Review Letters 64, 17, 2058 (1990)

[16] Handbook on Semiconductors , Vol. 1 p721-816 (1992).

[17] Applied Physics Letters 74, 2507 (1999)

[18] Physical Review B (Rapid) 55, 24, 16037 (1997)

Research Summary

My current principle research interests are magnetic semiconductors and magnetic metals, nanostructured ferromagnets, nanomagnetism and spintronics. I am involved in materials and device development and fundamental and applied experimental studies. Our group has extensive materials development capabilities and we are part of the EPSRC UK National center for epitaxial materials. [1] group website

[1] http://www.nottingham.ac.uk/~ppzgan/spin/

lab

Recent Publications

Past Research

I have worked very extensively for the last 10 year on ferromagnetic semiconductors. I have carried out important work elucidating the electronic and magnetic properties of ferromagnetic semiconductors including demonstrating the key role of Mn interstitial impurities, and achieving world record Curie temperatures. These achievements were reported in a series of papers[1],[2],[3],[4] which have already had a very large impact. These investigations have shed new light on single domain magnetic anisotropies[5],[6],[7],[8] and anisotropic magnetoresistance[9] leading to the discovery of several new phenomena, including Coulomb blockade anisotropic magnetoresistance[10],[11], and to patents and potential device applications.

My earlier research work was on the electrical transport properties of metals; particularly amorphous metals, alloys and transition metals. My contributions to this field are summarised in a Physics Reports review monograph[12].

For the last 25 years I have worked mostly on semiconductors. This initially involved low dimensional electron systems realised III-V semiconductor heterostructures fabricated by Molecular Beam Epitaxy (MBE) and subsequently processed by optical and electron beam lithography. Much of the work has involved nanostructured devices. I have worked extensively with cryogenic systems down to 10mK and high magnetic fields up to 70 Tesla.

I worked for many years on the Integer Quantum Hall effect (IQHE). My work on IQHE resistance standards, in collaboration with the National Physical Laboratory, led to the highest precision measurement of quantum Hall resistance ever achieved at the time[13]. I also carried out extensive work on the Fractional Quantum Hall effect, Wigner crystallization and 2D bi-layers in 2D hole devices. I was involved in the development of MBE grown p-type 2D devices with world record hole mobility[14] . Much of my work has focused on new quantum effects in electrical transport including studies of mesoscopic devices and ballistic transport. A major achievement of this period was the demonstration in mesoscopic conductors of a new phenomenon; Universal Thermopower Fluctuations[15], which are closely related to Universal Conductance Fluctuations.

I am an expert on thermoelectric effects and much of my early career involved experimental studies of thermoelectric effects in metals and semiconductors. I and wrote the chapter on thermoelectric effects in low dimensional and mesoscopic semiconductors in the definitive work Handbook on Semiconductors[16] , Vol. 1 p721-816 (1992) with Prof. P N Butcher.

I have also carried out extensive work on demonstrating the existence of, and potential for, nano-magnetometry[17], and novel magnetoresistance effects[18] in hybrid ferromagnet/ semiconductor devices.

[1] Applied Physics Letters 81, 16, 3010 (2002)

[2] Applied Physics Letters 81, 26, 4991 (2002)

[3] Physical Review Letters, 92 037201 (2004)

[4] Physical Review B 72 165204 (2005)

[5] Physical Review B (Rapid) 71, 121302 (2005)

[6] Physical Review Letters: 96 117207 (2006))

[7] Physical Review Letters, 95, 217204 (2005)

[8] Physical Review Letters, 100, 047202 (2008)

[9] Physical Review Letters 99, 147207 (2007)

[10] Physical Review Letters 94, 127202 (2005)

[11] Physical Review Letters: 97, 077201 (2006)

[12] Physics Reports 170, 265-324 (1992)

[13] Physical Review Letters 66, 969 (1991)

[14] Applied Physics Letters 65, 16, 2054 (1994).

[15] Physical Review Letters 64, 17, 2058 (1990)

[16] Handbook on Semiconductors , Vol. 1 p721-816 (1992).

[17] Applied Physics Letters 74, 2507 (1999)

[18] Physical Review B (Rapid) 55, 24, 16037 (1997)

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