摘要:

Josephson junctions were fabricated at the interface of YBa2Cu3O7−x(YBCO) and Nd1.85Ce0.15CuO4−y(NCCO) in heteroepitaxially grown superconducting bilayers. Devices of various configurations and sizes were fabricated, and they display a resistively shunted junction likeI–Vcharacteristics with hysteresis at low temperatures. A clear ac Josephson effect was observed under microwave irradiation, and critical currents were completely suppressible by external magnetic fields. Oxygen diffusion or charge diffusion at the interface are possible origins for the barrier formation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114813

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the effect of hydrostatic pressure up to 8 kbar on magnetoelastic, magnetic, and transport properties in the temperature range 10–300 K. An increase of Curie temperatureTcwith pressure &Dgr;Tc/&Dgr;p=2.6 K/kbar was determined from ac susceptibility measurements. The anomalies in resistivity and magnetovolume effects are significantly suppressed by pressure but the temperatures of these anomalies increased with pressure with the same slope asTc. These results indicate that impurity state of yttrium rather than lattice parameter reduction is responsible for the large increase in the magnetoresistance observed in the doped compound. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114814

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Iron grown on room‐temperature CaF2/Si(111) substrates form two‐dimensional arrays of nanometer‐sized superparamagnetic islands. Deposition of Ag on the Fe/CaF2/Si(111) produced a superparamagnetic response where the effective moment was proportional to the number of Fe islands covered by an average‐sized Ag island. The nonmagnetic Ag overlayer mediates a long‐range exchange between neighboring Fe islands within an individual Ag island. Monte Carlo methods are used to examine ordering in two dimensions and to set minimum interisland coupling strengths. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114815

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In contrast to preceding methods valid only for noninteracting many‐particle assemblies, we describe a theory applicable to two‐dimensional recording media, which includes interactions between particles through a mean‐field model. Expressions are obtained for the angular dependence of magnetic remanences parallel and perpendicular to the applied field. We define a quantity independent of interaction, theremanentmagnetizationdirection, which provides a realistic distribution of easy axes. From this distribution, plus saturation squareness measurements, the interaction strength may be estimated. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114816

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Amorphous nanoclusters of chromium and titanium silicides have been synthesized by implanting 35 keV chromium and 30 keV titanium ions, at a fluence of 1×1017cm−2in amorphous silica. The cluster stoichiometries were [Cr]/[Si]=1.6±0.3 and [Ti]/[Si]=1.1±0.3, respectively, as obtained by energy dispersive spectroscopic x‐ray microanalysis and confirmed by x‐ray photoelectron spectroscopy analysis. Titanium‐implanted ions are more reactive than chromium ones in terms of the formation of chemical bonds with silicon of the host silica matrix. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114817

出版商:AIP    

年代:1995

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.115556

出版商:AIP    

年代:1995

数据来源: AIP