Magnetic properties of polycrystalline Sm{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}} at high magnetic fields
- Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05389-970, Sao Paulo, SP (Brazil)
- Department of Inorganic and Analytical Chemistry, Hebrew University, Jerusalem 91904 (Israel)
- Institute for Pure and Applied Physical Sciences, UCSD, La Jolla, California 92093-0075 (United States)
We have performed measurements of ac magnetic susceptibility {chi}{sub ac} as a function of temperature and magnetic field on polycrystalline specimens of Sm{sub 2{minus}{ital x}}Ce{sub {ital x}}CuO{sub 4{minus}{ital y}} (0.15{le}{ital x}{le}0.18) prepared from a sol-gel precursor. All the samples studied show a striking double resistive superconducting transition. One of the resistive transitions occurs at a higher temperature {ital T}{sub {ital ci}} and the other one at a lower Josephson-coupling temperature {ital T}{sub {ital cj}}. Magnetic measurements reveal the appearance of superconductivity below {ital T}{sub {ital cj}} which is evident from the resistive component {chi}{double_prime} which peaks only at {ital T}{sub {ital cj}}. Measurements made on pellets and crushed samples with average grain size {approximately}1 {mu}m show essentially the same features. This suggests that Josephson coupling occurs inside physical grains with dimensions close to 5 {mu}m. We have also utilized the behavior of the peak in the {chi}{double_prime} component as a function of applied magnetic fields to build a {ital H} vs {ital T} phase diagram for these compounds. Some interesting features were observed in this {ital H} vs {ital T} phase diagram: (1) a {ital H}{sup {alpha}}, {alpha}=2/3, dependence at low applied magnetic fields ({ital H}{le}2 kOe) and high temperatures, and (2) an abrupt increase in the magnitude of the exponent at high fields and low temperatures. The behavior at low fields and high temperatures suggests that the magnetic response of the system is mainly controlled by a disordered Josephson network. Possible connections between these two different behaviors are discussed. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 280105
- Report Number(s):
- CONF-951101-; ISSN 0021-8979; TRN: 9608M0176
- Journal Information:
- Journal of Applied Physics, Vol. 79, Issue 8; Conference: 40. conference on magnetism and magnetic materials, Philadelphia, PA (United States), 6-9 Nov 1995; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ac susceptibility and transport critical-current density of polycrystalline c-axis-oriented YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films: Josephson tunneling and d-wave pairing
Properties of polycrystalline (Nd{ital {sub 1{minus}x}}Gd{ital {sub x}}){sub 1.85}Ce{sub 0.15}CuO{sub 4{minus}{ital y}} compounds