Electron spin resonance and magnetic susceptibility suggest superconductivity in Na doped WO3samples |
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| Authors: | A Shengelaya S Reich Y Tsabba KA Müller |
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| Institution: | Physik-Institut der Universit?t Zürich, 8057, Zürich, Switzerland
Department of Materials and Interfaces, The Weizmann Institute of Science, 76100, Rehovot, Israel
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| Abstract: | In WO3 doped with Na (WO3:Na) an Electron Spin Resonance (ESR) signal with unresolved fine and/or hyperfine structure is detected and used as a probe
for the state of the carriers. Using the saturation method we determined the spin-lattice relaxation rate 1/
T
1
of these paramagnetic centers. Upon cooling below 100 K, 1/
T
1
decreases markedly, as known to occur in NMR when a gap opens in the superconducting state. At low temperatures, 1/
T
1
quantitatively follows BCS behavior with a gap K or 2 . The magnetic susceptibility exhibits a strong difference between magnetic-field cooled and zero-field cooled regimes below
which also supports a so far unknown superconducting phase resulting from Na doping.
Received 14 April 1999 and Received in final form 6 September 1999 |
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| Keywords: | PACS 74 72 -h High-Tc compounds - 76 30 -v Electron paramagnetic resonance and relaxation |
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