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Methods & Techniques

Magnetotransport

Spectroscopy
Raman
Transport Properties
Magnetotransport
Low-frequency Noise
Low Noise Measurements
Magnetic properties
SQUID Magnetometry
Torque Magnetometry
Thermodynamic properties
Specific Heat
Material Analysis
X-Ray Diffraction
AFM/STM
LEED/RHEED
SEM/EDX
Thin films & nanostructures
Lithography
Thin Film Deposition
RIE/IBE
ULT
µK System
Dilution Refrigerators
ULT Thermometry
Bulk materials
Crystal Growth
Oxford split-coil cryostat (jpeg 35k)Split-coil magnet cryostat with optical access

A variety of magneto-transport measurement setups are available at the Walther-Meissner-Institut. In most of these systems, the magnetic field is generated by means of a single superconducting coil (solenoid) held at liquid He temperatures in the 4He space of the magnet cryostat. Several magnet systems with maximum fields ranging from μ0H = 8 T to μ0H = 17 T are routinely used at the WMI.

For magneto-transport experiments, the sample is mounted on a dip-stick and inserted into a separate cryostat located within the magnet system. Sample temperatures of 1.7 K < T < 390 K can thus be straightforwardly adjusted. For low-temperature experiments, 3He or dilution refrigerator stages are inserted into the magnet cryostats, allowing sample temperatures down to about 20 mK.

In addition, a superconducting split-coil magnet with |μ0H| < 8 T also is operational at the WMI. This system allows optical access to the sample space both along the magnetic field axis as well as perpendicular to it, and is equipped with a variable temperature insert for 1.7 K < T < 390 K. A vector magnet system (vertical field μ0H = 1.6 T, horizontal field μ0H = 0.35 T), as well as an ultra-low-temperature setup with magnetic fields of up to 8 T and sample temperatures below 1 mK offer further experimental possibilities.

Mark's cryostat (jpeg, 36k)Superconducting magnet cryostat

Magnetotransport experiments on highly anisotropic materials, such as organic metals or high-Tc superconductors, require precise orientation of the magnetic field. For this purpose, an insert with a two-axes rotation stage has been built at the WMI. The insert allows in-situ continuous rotations with a resolution of better than 0.01°. It is compatible with 4He and 3He cryostats operating in the temperature range from 0.4 to 300 K in the 17 T superconducting magnet. It can also be used in the 20 MW magnet at the Grenoble High Magnetic Field Lab, providing steady fields up to 28 T. The rotation is driven by a piezomotor insensitive to large stray fields generated by the magnet.

The rotation stage accommodates a nonmagnetic miniature pressure cell for magnetotransport measurements under pressure of up to 10 kbar.

A bigger cell, for pressures up to 15 kbar, is used for measurements in a dilution refrigerator: at fixed field orientations (up to 17 T) or, at lower field strengths, with the possibility of rotation (two-axes rotation; vector magnet with vertical field 1.6 T; horizontal field 0.35 T).

2-axes rotation unit (jpeg, 17k)
Two-axes rotation unit for magnetotransport measurements, pressure cell, and sample holder with two organic metal crystals and pressure gauge