L. A. Yeoh

Piezoelectric rotator for studying quantum effects in semiconductor nanostructures at high magnetic fields and low temperatures

We report the design and development of a piezoelectric sample rotation system, and its integration into an Oxford Instruments Kelvinox 100 dilution refrigerator, for orientation-dependent studies of quantum transport in semiconductor nanodevices at millikelvin temperatures in magnetic fields up to 10 T. Our apparatus allows for continuous in situ rotation of a device through >100° in two possible configurations. The first enables rotation of the field within the plane of the device, and the second allows the field to be rotated from in-plane to perpendicular to the device plane. An integrated angle sensor coupled with a closed-loop feedback system allows the device orientation to be known to within ±0.03° while maintaining the sample temperature below 100 mK.

Using a tunable quantum wire to measure the large out-of-plane spin splitting of quasi two-dimensional holes in a GaAs nanostructure.

The out-of-plane g-factor g([perpendicular])(*) for quasi two-dimensional (2D) holes in a (100) GaAs heterostructure is studied using a variable width quantum wire. A direct measurement of the Zeeman splitting is performed in a magnetic field applied perpendicular to the 2D plane. We measure an out-of-plane g-factor up to g([perpendicular])(*) = 5, which is larger than previous optical studies of g([perpendicular])(*) and is approaching the long predicted but never experimentally verified out-of-plane g-factor of 7.2 for heavy holes.

Electrical control of the sign of the g factor in a GaAs hole quantum point contact

Zeeman splitting of one-dimensional hole subbands is investigated in quantum point contacts fabricated on a (311)-oriented GaAs-AlGaAs heterostructure. Transport measurements can determine the magnitude of the

Electrically controlled piezo-rotator for studying semiconductor nanostructures at milli-Kelvin temperatures and high magnetic fields

g

Mapping the anisotropy of the Zeeman spin splitting of one-dimensional heavy holes in a GaAs quantum point contact

factor, but cannot usually determine the sign. Here we use a combination of tilted fields and a unique off-diagonal element in the hole

Manifestation of a non-Abelian Berry phase in a p-type semiconductor system

g

Noncollinear paramagnetism of a GaAs two-dimensional hole system.

tensor to directly detect the sign of

Publisher's Note: Manifestation of a non-Abelian Berry phase in a p -type semiconductor system [Phys. Rev. B 93 , 205424 (2016)]

{g}^{*}

Publisher's Note: Electrical control of the sign of the g factor in a GaAs hole quantum point contact [Phys. Rev. B 94 , 041406(R) (2016)]

. We are able to tune not only the magnitude, but also the sign of the

Mapping the anisotropic Lande g-factor tensor of 1D GaAs holes in all 3 spatial directions

g