Hypersensitive macroscopic manipulation of
quantum many-body states
M. Bartkowiak, S. Gerber and M. Kenzelmann from the Paul Scherrer Institut, Switzerland, have
developed a goniometer sample holder for neutron scattering, which permits in-situ tuning of
complex quantum states at low temperatures (100 mK) and high magnetic fields (up to 12 T) [1].
The device is based on a purpose-built, non-magnetic ANGt50/LT goniometer of attocube’s open
loop positioners. It has an angular range of ±3.6° and is sufficiently compact to fit a dilution
refrigerator – cryomagnet environment.
With this device, the magnetic domain population in so-called Ce-115 superconductors could
be controlled by altering the alignment of the sample to the magnetic field direction [1,2].
Therewith a binary switching behavior has been found which provides strong evidence for a
direct coupling of magnetism and unconventional superconductivity in the vicinity of quantum
criticality. Population of the Q h (orange) and Q v (grey) magnetic domains in the so-called Q-phase
of the compound CeCoIn 5 is shown as a function of the tilt angle with respect to the external
magnetic field. For |Ψ| ≥ 0.05° a mono-domain population is found, which can be macroscopically
switched (modified from [1]).
[1] S. Gerber et al., Nature Physics 10, 126 (2014).
[2] D. G. Mazzone et al., Scientific Reports 8, 1295 (2018).
Sample positioning in scanning transmission x-ray
microscope at SLAC
We use attocube linear stages with optical and resistive encoders for positioning of samples
relative to high resolution x-ray optics in a scanning transmission x-ray microscope.
The picture shows a magnetic excitation called “soliton” that is the result of a spin polarized
current injected into a thin ferromagnetic Co/Pt multilayer. The injected spin causes a localized
oscillation of the magnetization at the spot where the current is injected, here a nano contact
with a 150 nm diameter in the center of the picture. Time resolved scanning transmission x-ray
microscopy using magnetic circular dichroism as a contrast mechanism is used to obtain an image
of the magnetic soliton.
Dr. Hendrik Ohldag, Stanford Synchrotron Radiation Laboratory, SLAC National Accelerator Laboratory.