Kevin van Hoogdalem
ContactDepartment of PhysicsUniversity of Basel Klingelbergstrasse 82 CH4056 Basel, Switzerland

CV
2012  Present  Postdoc in the Condensed Matter Theory group of the University of Basel, in the group of Prof. Dr. D. Loss 
2008  2012  PhD student in the Condensed Matter Theory group of the University of Basel, in the group of Prof. Dr. D. Loss 
2006  2008  Master in Applied Physics at Delft University of Technology 
2001  2006  Bachelor in Applied Physics at Delft University of Technology 
Research interests
 Spin hydrodynamics
 Spin transport in nonitinerant systems
 Molecular magnets
 Quantum random walks
Popular articles
Quantum random walks, Nederlands Tijdschrift voor Natuurkunde 75, page 384388, November 2009 (in Dutch)Publications
Show all abstracts.1.  Ultrafast magnontransistor at room temperature 
Kevin A. van Hoogdalem and Daniel Loss. arXiv:1209.5594v1
We study sequential tunneling of magnetic excitations in nonitinerant systems (either magnons or spinons) through triangular molecular magnets. It is known that the quantum state of such molecular magnets can be controlled by application of an electric or a magnetic field. Here, we use this fact to control the flow of a spin current through the molecular magnet by electric or magnetic means. This allows us to design a system that behaves as a magnontransistor. We show how to combine three magnontransistors to form a NANDgate, and give several possible realizations of the latter, one of which could function at room temperature using transistors with a 11 ns switching time.
 
2.  Magnetic textureinduced thermal Hall effects 
Kevin A. van Hoogdalem, Yaroslav Tserkovnyak (UCLA), and Daniel Loss. arXiv:1208.1646v1
Magnetic excitations in ferromagnetic systems with a noncollinear ground state magnetization experience a fictitious magnetic field due to the equilibrium magnetic texture. Here, we investigate how such fictitious fields lead to thermal Hall effects in twodimensional insulating magnets in which the magnetic texture is caused by spinorbit interaction. We find that, besides the wellknown geometric texture contribution to the fictitious magnetic field in such systems, there exists also an equally important but often neglected contribution due to the original spinorbit term in the free energy. We consider the different possible ground states in the phase diagram of a twodimensional ferromagnet with spinorbit interaction: The spiral state and the skyrmion lattice, and find that thermal Hall effects can occur in certain domain walls as well as the skyrmion lattice.
 
3.  Frequency dependent transport through a spin chain 
Kevin A. van Hoogdalem and Daniel Loss. Phys. Rev. B 85, 054413 (2012).; arXiv:1111.4803v1.
Motivated by potential applications in spintronics, we study frequency dependent spin transport in nonitinerant onedimensional spin chains. We propose a system that behaves as a capacitor for the spin degree of freedom. It consists of a spin chain with two impurities a distance $d$ apart. We find that at low energy (frequency) the impurities flow to strong coupling, thereby effectively cutting the chain into three parts, with the middle island containing a discrete number of spin excitations. At finite frequency spin transport through the system increases. We find a strong dependence of the finite frequency characteristics both on the anisotropy of the spin chain and the applied magnetic field. We propose a method to measure the finitefrequency conductance in this system.
 
4.  Rectification of spin currents in spin chains 
Kevin A. van Hoogdalem and Daniel Loss. Phys. Rev. B 84, 024402 (2011).; arXiv:1102.4801.
We study spin transport in nonitinerant onedimensional quantum spin chains.
Motivated by possible applications in spintronics, we consider rectification
effects in both ferromagnetic and antiferromagnetic systems. We find that the
crucial ingredients in designing a system that displays a nonzero
rectification current are an anisotropy in the exchange interaction of the spin
chain combined with an offset magnetic field. For both ferromagnetic and
antiferromagnetic systems we can exploit the gap in the excitation spectrum
that is created by a bulk anisotropy to obtain a measurable rectification
effect at realistic magnetic fields. For antiferromagnetic systems we also find
that we can achieve a similar effect by introducing a magnetic impurity,
obtained by altering two neighboring bonds in the spin Hamiltonian.
 
5.  Implementation of the quantum walk step operator in lateral quantum dots 
Kevin A. van Hoogdalem and M. Blaauboer. Phys. Rev. B 80, 125309 (2009).
We propose a physical implementation of the step operator of the discrete quantum walk for an electron in a onedimensional chain of quantum dots. The operating principle of the step operator is based on locally enhanced Zeeman splitting and the role of the quantum coin is played by the spin of the electron. We calculate the probability of successful transfer of the electron in the presence of decoherence due to quantum charge fluctuations, modeled as a bosonic bath. We then analyze two mechanisms for creating locally enhanced Zeeman splitting based on, respectively, locally applied electric and magnetic fields and slanting magnetic fields. Our results imply that a success probability of > 90% is feasible under realistic experimental conditions.
