研究领域

Physical & Theoretical Chemistry

My research lies in the area of condensed matter theory, where the aim is to characterise and understand the physical properties of materials consisting of enormously large numbers of interacting particles. Of particular interest are 'strongly-correlated' systems, in which the interactions between particles are simply too large to ignore or treat using mean-field approaches. One instead develops quantum many-body techniques to determine the underlying physical behaviour. I am currently interested in many-body effects on the nanoscale, as observed in the electronic conductance of single molecules, carbon nanotubes and other so-called 'quantum dot' devices. These kinds of system present exciting prospects for novel electronic devices, in part due to their innate tunability: the electrons' energy levels and their mutual Coulomb and exchange interactions can all be adjusted, allowing controlled access to a wide range of interesting many-body phenomena. In the classic example, the quantum dot is set up so that it contains an unpaired electron in its outermost orbital. The large energetic cost to remove this electron, or add another, means that the dot cannot conduct electricity simply by electrons independently tunnelling on and off, one at a time. But -- remarkably -- experiments nonetheless show perfect conductance at low temperatures. The enhanced conductance is due to the Kondo effect, where correlated motion of the electrons allows them to pass through the quantum dot even though sequential, one-at-a-time tunnelling is not energetically feasible. To understand this effect, and more exotic, related phenomena, we analyze the many-body Hamiltonians that describe the key features of the experiment, using a combination of analytical and numerical methods. A selection of recent publications is listed below.

近期论文

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Martin R. Galpin, David E. Logan and H. R. Krishnamurthy Quantum Phase Transition in Capacitively Coupled Double Quantum Dots Phys. Rev. Lett. 94, 186406 (2005). Martin R. Galpin and David E. Logan Single-particle dynamics of the Anderson model: a two-self-energy description within the numerical renormalization group approach J. Phys.: Condens. Matter 17, 6959 (2005). Martin R. Galpin, David E. Logan and H. R. Krishnamurthy Renormalization group study of capacitively coupled double quantum dots J. Phys.: Condens. Matter 18, 6545 (2006). Martin R. Galpin, David E. Logan and H. R. Krishnamurthy Dynamics of capacitively coupled double quantum dots J. Phys.: Condens. Matter 18, 6571 (2006). Andrew K. Mitchell, Martin R. Galpin and David E. Logan Gate voltage effects in capacitively coupled double quantum dots Europhys. Lett. 76, 95 (2006). David E. Logan and Martin R. Galpin Evolution and destruction of the Kondo effect in a capacitively coupled double dot system Int. J. Mod. Phys. B 21, 2191 (2007). Frithjof B. Anders, David E. Logan, Martin R. Galpin and Gleb Finkelstein Zero-bias conductance in carbon nanotube quantum dots Phys. Rev. Lett. 100, 086809 (2008) Martin R. Galpin and David E. Logan Anderson impurity model in a semiconductor Phys. Rev. B 77, 195108 (2008) Martin R. Galpin and David E. Logan A local moment approach to the gapped Anderson model Eur. Phys. J. B 62, 129 (2008) David E. Logan and Martin R. Galpin Tunneling transport and spectroscopy in carbon nanotube quantum dots J. Chem. Phys. 130, 224503 (2009) Martin R. Galpin, Anne B. Gilbert and David E. Logan A local moment approach to the degenerate Anderson impurity model J. Phys.: Condens. Matter 21, 375602 (2009) David E. Logan, Christopher J. Wright and Martin R. Galpin Correlated electron physics in two-level quantum dots: phase transitions, transport, and experiment Phys. Rev. B 80, 125117 (2009) Martin R. Galpin, Frederic W. Jayatilaka, David E. Logan and Frithjof B. Anders Interplay between Kondo physics and spin-orbit coupling in carbon nanotube quantum dots Phys. Rev. B 81, 075437 (2010) Frederic W. Jayatilaka, Martin R. Galpin and David E. Logan Two-channel Kondo physics in tunnel-coupled double quantum dots Phys. Rev. B 84, 115111 (2011) Christopher J. Wright, Martin R. Galpin and David E. Logan Magnetic field effects in few-level quantum dots: Theory and application to experiment Phys. Rev. B 84, 115308 (2011) Simon. J. Chorley, Martin R. Galpin, Frederic W. Jayatilaka, Charles G. Smith, David E. Logan and Mark R. Buitelaar Tunable Kondo Physics in a Carbon Nanotube Double Quantum Dot Phys. Rev. Lett. 109, 156804 (2012) Andrew K. Mitchell, Thomas F. Jarrold. Martin R. Galpin and David E. Logan Local moment formation and Kondo screening in impurity trimers J. Phys. Chem. B 117, 12777 (2013) Martin R. Galpin, Andrew K. Mitchell, Jesada Temaismithi, David E. Logan, Benjamin Beri and Nigel R. Cooper Conductance fingerprint of Majorana fermions in the topological Kondo effect Phys. Rev. B. 89, 045143 (2014) Andrew K. Mitchell, Martin R. Galpin, Samuel Wilson-Fletcher, David E. Logan and Ralf Bulla Generalized Wilson chain for solving multichannel quantum impurity problems Phys. Rev. B. 89, 121105(R) (2012) David E. Logan, Adam P. Tucker and Martin R. Galpin Common non-Fermi liquid phases in quantum impurity physics