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in creator/contributor: "Cooke, D.W."

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Magnetic ordering in (Y sub 1-x Pr sub x )Ba sub 2 Cu sub 3 O sub 7 as evidenced by muon spin relaxation

Using the zero-field-muon-spin-relaxation ({mu}SR) technique we have found clear evidence for antiferromagnetic ordering of Cu moments within the CuO planes of (Y{sub 1-x}Pr{sub x})Ba{sub 2}Cu{sub 3}O{sub 7}. The Neel temperatures are approximately 285 K, 220 K, 35 K, 30 K, and 20 K for x = 1, 0.8, 0.6, 0.58, and 0.54, respectively. For x = 0.50 we observe a fast-relaxing component of the muon polarization in addition to a long-time tail, reminiscent of spin-glass behavior. This region of the p… more

Date: January 1, 1989

Creator: Cooke, D.W.; Kwok, R.S.; Jahan, M.S.; Lichti, R.L.; Adams, T.D.; Boekema, C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Luminescence from defects and impurity centers in yttrium oxide

High-purity (99.999%) Y{sub 2}O{sub 3} powder is used as a starting material for fabricating high-temperature superconductors (HTS), and is frequently found as an unreacted second phase in the final product. We have found that as-received Y{sub 2}O{sub 3} contains Tb{sup 3+} paramagnetic impurity ions as determined by TSL and emission-spectra measurements. Deep luminescence traps (presumably Tb{sup 4+} ions) are formed in Y{sub 2}O{sub 3} when it is exposed to {gamma}-rays, x rays, or fluoresce… more

Date: January 1, 1989

Creator: Jahan, M.S.; Cooke, D.W.; Bennett, B.L.; Hults, W.L.; Maez, M.A.; Ott, K.C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Temperature dependence of anomalous muonium hyperfine interactions in silicon

The temperature dependence of the anomalous muonium hyperfine interaction has been measured in silicon. Between 5 and 150 K, an approximately 1% decrease is observed and attributed to interaction with the silicon host phonons.

Date: January 1, 1980

Creator: Blazey, K.W.; Brown, J.A.; Cooke, D.W.; Dodds, S.A.; Estle, T.L.; Heffner, R.H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Heavy fermion materials. [UBe/sub 13/]

The heavy-fermion ground state occurs in a few select metallic compounds as a result of interactions between f-electron and conduction-electron spins. A characteristically large electronic heat capacity at low temperature indicates that the effective electron mass of these materials is more than two orders of magnitude greater than that expected for a free-electron metal. This heavy-fermion ground state can become superconducting or antiferromagnetic, exhibiting very unusual properties. These m… more

Date: January 1, 1986

Creator: Smith, J.L. & Cooke, D.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-frequency cavity applications and measurements of high-temperature superconductors

A potentially important application of high-temperature superconductors will be high-frequency accelerating cavities. Currently these materials are not competitive with Nb at liquid helium temperature or with Cu at room temperature. However, available data on high-quality single crystals suggest that the relatively poor rf properties (high surface resistance and low surface magnetic field) of bulk and film specimens are due to materials properties that can be eliminated by improved processing t… more

Date: January 1, 1989

Creator: Cooke, D.W. & Gray, E.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

DEMUR: double electron muon resonance

The details of a general theory of DEMUR are presented, with examples of current experimental interest: quartz, where the hyperfine interaction is nearly isotropic; and silicon, wherein an anisotropic species has been found. The theory will be compared with experimental data.

Date: January 1, 1980

Creator: Vanderwater, D.A.; Brown, J.A.; Cooke, D.W.; Dodds, S.A.; Estle, T.L.; Heffner, R.H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transverse- and zero-field. mu. SR (muon-spin-rotation) investigation of magnetism and superconductivity in (Y sub 1-x Pr sub x )Ba sub 2 Cu sub 3 O sub 7

Zero-field muon-spin-rotation ({mu}SR) measurements on (Y{sub 1-x}Pr{sub x})Ba{sub 2}Cu{sub 3}O{sub 7} (x = 1.0, 0.8, 0.6, and 0.54) show evidence for antiferromagnetic ordering of the Cu moments within the Cu--O planes, with Neel temperatures 285,220, 35, 30, and 20 K respectively. For x = 1.0 the local muon magnetic field is {approximately}16 mT, but decreases to {approximately}12 mT at 17 K, due to additional magnetic ordering. The zero-field data, in conjunction with transport data, allow c… more

Date: January 1, 1990

Creator: Cooke, D.W.; Jahan, M.S.; Kwok, R.S. (Los Alamos National Lab., NM (USA)); Lichti, R.L.; Adams, T.R. (Texas Tech Univ., Lubbock, TX (USA)); Boekema, C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

RF properties of high temperature superconductors: Cavity methods

A description of cavities used in the study of the microwave properties of the high-temperature superconductors is followed by a lumped-circuit analysis of the coupling of transmission lines and resonators. The frequency dependence of the reflected and transmitted microwave power and the character of transient cavity response are analyzed. Techniques are discussed for the introduction of samples of the high-temperature superconductors into microwave cavities. Following a discussion of sample su… more

Date: January 1, 1990

Creator: Portis, A.M. (California Univ., Berkeley, CA (USA)); Cooke, D.W. & Gray, E.R. (Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Pyroelectricity and its role in optical damage of potassium titanyl phosphate crystals

The origin of optical damage in potassium titanyl phosphate (KTP) crystals has been vigorously investigated since its introduction as a nonlinear optical material in 1976. It is well known that this material exhibits a laser damage threshold that limits its use in many high average-power applications, especially frequency doubling of Nd-doped lasers. Both photochromic and electrochromic damage can be induced in KTP. Until recently, it was thought that these two types of damage were distinctly d… more

Date: December 1, 1996

Creator: Cooke, D.W.; Bennett, B.L.; Thomas, J.C. & Petrin, R.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Measurement of point defect energetics in potassium dihydrogen phosphate (KDP). Final report

Potassium dihydrogen phosphate (KDP) in the normal and deuterated form (KD*P) exhibits excellent electrooptical and nonlinear optical properties and is commonly used in frequency conversion applications. Frequency doubling (2 {omega}) of Nd:YAG or Nd:YLF laser fundamental output at 1.06 {micro}m produces visible radiation at 532 nm with relatively good conversion efficiency. Frequency tripling (3{omega}) and quadrupling (4{omega}) are also utilized for production of ultraviolet (uv) radiation a… more

Date: October 1, 1997

Creator: Cooke, D.W.; Muenchausen, R.E. & Bennett, B.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Damage Accumulation in MgAl{sub 2}O{sub 4} and Yttria-Stabilized ZrO{sub 2} by Xe-Ion Irradiation

Magnesium-aluminate spinel (MAS) and yttria-stabilized zirconia (YSZ) are being considered for use as ceramic matrices in proliferation resistant fuels and radioactive storage systems, and may be used either as individual entities or as constituents in multicomponent ceramic systems. It is worthwhile, therefore, to compare radiation damage in these two potentially important materials when subjected to similar irradiation conditions, e.g., ion beam irradiation. To compare radiation damage proper… more

Date: April 25, 1999

Creator: Afanasyev-Charkin, I.V.; Gritsyna, V.T.; Cooke, D.W.; Bennett, B.L. & Sickafus, K.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department