Kevin van Hoogdalem


Department of Physics
University of Basel
Klingelbergstrasse 82
CH-4056 Basel, Switzerland

email:view address

tel: +41 (0)61 267 3695


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

Popular articles

Quantum random walks, Nederlands Tijdschrift voor Natuurkunde 75, page 384-388, November 2009 (in Dutch)


Show all abstracts.

1.  Ultrafast magnon-transistor at room temperature
Kevin A. van Hoogdalem and Daniel Loss.

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 magnon-transistor. We show how to combine three magnon-transistors to form a NAND-gate, 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 texture-induced thermal Hall effects
Kevin A. van Hoogdalem, Yaroslav Tserkovnyak (UCLA), and Daniel Loss.

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 two-dimensional insulating magnets in which the magnetic texture is caused by spin-orbit interaction. We find that, besides the well-known 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 spin-orbit term in the free energy. We consider the different possible ground states in the phase diagram of a two-dimensional ferromagnet with spin-orbit 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 one-dimensional 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 finite-frequency 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 non-itinerant one-dimensional 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 non-zero 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 one-dimensional 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.