Magnetic penetration depth in Ni- and Zn-doped YBa{sub 2}(Cu{sub 1{minus}{ital x}}{ital M}{sub {ital x}}){sub 3}O{sub 7} films
- Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
The penetration depth {lambda}({ital T}) in YBa{sub 2}(Cu{sub 1{minus}{ital x}}{ital M}{sub {ital x}}){sub 3}O{sub 7} films, with {ital M}=Ni or Zn and nominal concentrations, 0.02{le}{ital x}{le}0.06, is obtained from the mutual inductance of coaxial coils on opposite sides of the films. Both Ni and Zn increase {lambda}(0) very rapidly, such that the superfluid density, {ital n}{sub {ital s}}(0){proportional_to}{lambda}{sup {minus}2}(0), decreases by a factor of 2 for each percent of dopant. The rapid increase in {lambda}(0) implies that disorder fills in the superconducting density of states at low energy, so that {ital N}{sub {ital S}}(0) is roughly 80--95 % of the normal-state density of states. An analytic {ital d}-wave theory, valid at {ital T}=0, finds that {lambda}(0) increases rapidly with disorder, but not as rapidly as observed. It is striking that the dependence of {lambda}({ital T}/{ital T}{sub {ital c}}) on {ital T}/{ital T}{sub {ital c}} does not change significantly as {ital x} increases from 2% to 6%, although it is different from undoped YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films. An {ital ad} {ital hoc} phenomenological model finds that one should expect this result. Finally, the values of {ital N}{sub {ital S}}(0) deduced from {lambda} are somewhat larger than values deduced from specific-heat measurements on Zn-doped YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, which also indicate increasing gaplessness with doping.
- Research Organization:
- Purdue Research Foundation
- DOE Contract Number:
- FG02-90ER45427
- OSTI ID:
- 26054
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 14 Vol. 51; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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