Very low-temperature search for superconductivity in semiconducting KTaO/sub 3/

Journal Article · Tue Jun 01 00:00:00 EDT 1982 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00683987· OSTI ID:5068635

Thompson, J R; Boatner, L A; Thomson, J O

A series of attempts have been made to detect the presence of superconductivity in semiconducting potassium tantalate (KTaO/sub 3/) single crystals. Semiconducting potassium tantalate has a number of properties in common with semiconducting SrTiO/sub 3/, which is superconducting below approx.0.3 K, with a critical temperature T/sub c/ that varies as a function of the carrier concentration. Both KTaO/sub 3/ and SrTiO/sub 3/ are perovskite-structure oxides and both materials are so-called incipient ferroelectrics that are characterized by high dielectric constants at low temperature. These common properties suggest that superconductivity might also be observed in semiconducting potassium tantalate. In the temperature range from 0.01 to 4.0 K, however, no evidence was found for superconductivity in KTaO/sub 3/ in the presence of magnetic fields of 10/sup -5/--10/sup -4/ T(i.e., 0.1--1 Oe). Below 1.5 K, the search for superconductivity in KTaO/sub 3/ was carried out using a /sup 3/He--/sup 4/He dilution refrigerator equipped with a SQUID magnetometer and an ac magnetometer. The system response was verified by measuring the paramagnetic susceptibility of DY/sub 2/O/sub 3/-doped KTaO/sub 3/. The failure to observe superconductivity in KTaO/sub 3/, while SrTiO/sub 3/ is an established superconducting material, may be related to the fact that the latter substance assumes a tetragonal symmetry phase at 105 K, while KTaO/sub 3/ remains cubic to low temperatures.

• Research Organization: Department of Physics, The University of Tennessee, Knoxville, Tennessee, and Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5068635
• Journal Information: J. Low Temp. Phys.; (United States), Vol. 47:5
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
POTASSIUM COMPOUNDS
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SEMICONDUCTOR MATERIALS
TANTALATES
ULTRALOW TEMPERATURE
ALKALI METAL COMPOUNDS
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
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OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
TANTALUM COMPOUNDS
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