LOW TEMPERATURE RESEARCH FACILITY

Resistivity, Magneto-resistance, and Hall Effect

Electrical transport measurements on materials are carried out as a function of temperature. This system makes use of a liquid helium cryostat that houses a 10 Tesla superconducting magnet. The temperature of a sample may be varied from 2 K to 300 K and can be held constant with an accuracy of +/- 0.05K. The collection of data and the regulation of sample temperature is computer controlled. Design and construction of much of this system was carried out by undergraduate physics majors at Brockport. A detailed discussion of this system was publushed in the Proceedings of the National Conference on Undergraduate Research. See the He4 cryostat (1.2K < T < 300K), with insert being leak tested.

A.C. Magnetic Susceptibility

Materials ac magnetic susceptibility is studied/measured using a Hartshorn Bridge as modified by Maxwell, and an SAR850 Lock-in-Detector in the same temperature range. In collaboration with D. I. Popov, the magnetic susceptibility and the resistivity have actually been measured simultaneously on the same sample on indium doped tin-lead telluride semiconducting samples with superconducting properties below 4.2 K, with obvious correlation, but not so obvious results.

D.C. Magnetic Susceptibility

Magnetization is measured using an Oxford Instruments RF SQUID magnetometer with a temperature range extanded down to 0.33K, using a Janis He3 refrigerator.

R. V. Mancuso and MZT are collaborating on reconciling a mechanical model of first- and second-order phase transitions with the magnetic counterparts, using A.C. and D.C. magnetic measurements.

Specific Heat

Low temperature measurements of sample's heat capacity is done using the pulse and/or the ac method. The ac technique is well suited for heat capacity measurements around phase transition temperatures. The set-up has been tested and run on indium doped tin-lead-tellurides, semiconductor materials with superconducting properties (in collaboration with D. I. Popov and S. A. Nemov) and ferric Chloride intercalated graphite, a 2D electronic and magnetic system (in collaboration with G. O. Zimmerman). The preliminary results on SnPbTe-In show a specific heat anomaly due to superconducting transition, which has been correlated with resistivity and susceptibility measurements. The preliminary results on the GIC's also show a phase transition below 2 K, just like previous results on different stage samples.

Materials and Systems of Interest