Anisotropic superconductivity inC4KHg
| Autor: | W. A. Kamitakahara, A. Chaiken, M. S. Dresselhaus, Dan A. Neumann, G. Dresselhaus, P. M. Tedrow, Terry P. Orlando |
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| Rok vydání: | 1990 |
| Předmět: | |
| Zdroj: | Physical Review B. 41:71-81 |
| ISSN: | 1095-3795 0163-1829 |
| Popis: | Superconducting transition temperatures between 0.7 and 1.5 K are reported for the stage-1 potassium-mercury graphite intercalation compound (GIC) C{sub 4}KHg. A number of experiments have been performed to investigate the differences between the C{sub 4}KHg samples at either extreme in {ital T}{sub {ital c}}. The only structural difference appears to be that the {beta} phase (characterized by a {ital c}-axis lattice constant {ital I}{sub {ital c}}=10.83 A) is consistently found in the lower-{ital T}{sub {ital c}} samples, while the higher-{ital T}{sub {ital c}} samples always contain only the {alpha} phase ({ital I}{sub {ital c}}=10.24 A). Adding a minute amount of hydrogen to the {ital T}{sub {ital c}}=0.8 K samples raises their transition temperature to 1.5 K. Measurements of the angular dependence of the critical-field suggest that the higher-{ital T}{sub {ital c}} samples have type-I character for a range of applied field orientations near {bold H}{parallel}{bold {cflx c}}. The temperature dependence of the upper critical field of C{sub 4}KHg shows extended linearity of {ital H}{sub {ital c}2}(T) for both types of samples. The critical field data of C{sub 4}KHg and other GIC's are discussed in light of multiband and anisotropic Fermi-surface models of superconductivity. The thermodynamic parameters obtained from the critical-fieldmore » experiments are compared to the specific-heat data of Alexander {ital et} {ital al}. A charge-density-wave hypothesis first proposed by DeLong and Eklund is suggested to explain the hydrogen-induced enhancement of {ital T}{sub {ital c}}.« less |
| Databáze: | OpenAIRE |
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