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  • 1
    Electronic Resource
    Electronic Resource
    Polarization analysis of the magnetic excitations in Fe65Ni35 Invar : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6069-6071 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Triple-axis inelastic polarized neutron measurements have been performed as a function of temperature on a single crystal of the Invar alloy Fe65Ni35 to distinguish longitudinal from transverse magnetic excitations in the magnetically ordered phase. Well below the Curie temperature of 501 K the magnetic excitation spectrum is dominated by conventional transverse spin-wave excitations, which in fact follow the predictions of spin-wave theory very well. In particular, we find no evidence for propagating longitudinal excitations in this system, in sharp contrast to the behavior observed in the amorphous Invar Fe86B14 material as well as the non-Invar amorphous system Fe40Ni40P14B6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355460
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature dependence of the magnetic excitations in ordered and disordered Fe72Pt28 : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6072-6074 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed inelastic neutron scattering measurements of the long-wavelength spin wave excitations of both ordered and disordered Fe72Pt28 single crystals below their critical temperatures, TC=510 and 375 K, respectively. The spin waves followed the expected E=Dq2 dependence, and the temperature-dependent spin stiffness D decreased as (T/TC)5/2, as expected for an isotropic ferromagnet. The extrapolated zero-temperature spin stiffness was D=98(4) meV A(ring)2 and 107(1) meV A(ring)2 for the disordered and ordered alloy, respectively. These values are significantly higher than the zero-temperature stiffness as determined by magnetization measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355461
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  • 3
    Electronic Resource
    Electronic Resource
    Modification to the HP 4274/75A LCR meters for investigation of device admittance under heavy forward bias conditions (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1265-1268 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The HP 4274A and HP 4275A LCR meters are widely used in the fields of semiconductor device characterization and component test. A bias voltage can be applied to the test samples either from an external power supply or from the built-in HP-IB controllable voltage source. The total series resistance of the bias filtering circuit should be in the range of about 100 Ω (HP 4275A). Detailed measurements and checking the measuring circuit diagrams revealed that the effective series resistance can be much higher, depending on the measuring range of the bridge. Therefore, admittance measurements on low-ohmic samples, especially Schottky or pn junctions under heavy forward bias conditions, are seriously affected by bias voltage reduction between the front HI/LOW terminals. Thus, e.g., a reduced apparent capacitance is measured. Consequently, the doping concentration near the pn junction will be determined erroneously. To avoid these effects, a bias regulating circuit is inserted into the LCR meters to guarantee the feedthrough of the bias voltage without any attenuation. Examples of admittance vs frequency and doping profiles near the pn junction of quaternary (Ga0.046In0.954As0.1P0.9) diodes are given for explanation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1137989
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  • 4
    Electronic Resource
    Electronic Resource
    A computer-controlled apparatus for performing pressure–composition–temperature measurements on metal hydrides with protium, deuterium, and tritium (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1775-1780 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An apparatus for measuring protium, deuterium, and tritium pressure–composition–temperature (PCT) thermodynamic equilibrium behavior on metal hydrides has been designed, constructed, and operated with deuterium at the Weapons Engineering Tritium Facility at Los Alamos National Laboratory. The apparatus is capable of performing PCT measurements with the three hydrogen isotopes at a maximum pressure of 3.45 MPa, and sample temperatures in the range 25–300 °C. A personal computer that controls the system provides the capability for manual or automated operation. Two deuterium PCT isotherms on palladium at 51 and 70 °C were measured with the apparatus in the automated mode to demonstrate its operation. Comparison of the resulting isotherms with literature data showed a plateau pressure at 70 °C in close agreement with the literature value (57.06 kPa versus literature value of 57.33 kPa). The deuterium capacity at 70 °C in palladium at the high end of the isotherm was measured both by the PCT apparatus and by weighing the sample before and after the PCT measurement. The deuterium capacity determined by the PCT apparatus (D/M=0.624 at 144.52 kPa) agreed well with the value determined by the weight difference measurement (D/M=0.628, at 144.52 kPa). These values agreed closely with the literature value (D/M=0.629 at 144.52 kPa). © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1347979
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetic field dependence of the elastic constants in Nd3Se4(abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3933-3933 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Most of the metallic rare-earth chalcogenides of RE3X4 type, where X stands for S, Se, Te, show marked elastic anomalies which appear either in conjunction with a structural transformation or with a magnetic ordering transition. In this contribution we report on results obtained from Nd3Se4 where the elastic constants display a particular magnetic field dependence. Single crystals were grown by a Bridgman–Stockbarger method and the three cubic elastic constants were measured by ultrasonic techniques as function of temperature and in an external magnetic field. The occurrence of magnetic ordering was proved independently by susceptibility measurements. Nd3Se4 has been found to order ferromagnetically at Tc =52 K. In the absence of an external magnetic field approaching Tc from above, the shear elastic constants (C11−C12)/2 softens by about 40%. Below Tc the elastic constants harden again where the increment of C11 follows the Brillouin function of the magnetization. An external magnetic field parallel to the propagation direction of the sound waves affects the elastic anomalies in the paramagnetic as well as in the ferromagnetic phase. Above Tc the sound velocities exhibit a H2 field dependence, as is expected from a magnetoelastic coupling mechanism. At temperatures smaller Tc the field-dependent elastic anomalies are related to the hysteresis loop M(H). The change of the elastic constants as a function of the magnetic field is proportional to the field derivative dM/dH. The coupling coefficient has an opposite sign for the C44 and (C11−C12)/2 shear elastic constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340610
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  • 6
    Electronic Resource
    Electronic Resource
    Elastic anomalies in iron-platinum invar alloys : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6537-6539 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Elastic anomalies in an Fe75Pt25 single crystal have been investigated by ultrasonic pulse echo and inelastic neutron scattering measurements in the temperature range 200 to 800 K. The single crystal which was grown by the Bridgman–Stockbarger process undergoes a magnetic transition at Tc = 370 K and a martensitic transformation at Ms = 200 K corresponding to a degree of order of S=0.7. Both ultrasonics and neutron scattering reveal a softening of the transverse modes below Tc. The excess elastic constants obey an M2 law as expected from a local magnetoelastic interaction model. The longitudinal ultrasonic velocities already start to soften at 700 K whereas the neutron data for the same acoustic branch do not show any anomaly down to 200 K. The observed q dependences of the acoustic branches point towards a softening confined to the very center of the Brillouin zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349899
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  • 7
    Electronic Resource
    Electronic Resource
    Integrated wavelength demultiplexer-receiver on InP (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 971-973 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detector stage comprising a photodiode, a field-effect transistor, and a load resistor, and a wavelength demultiplexer have been monolithically integrated in the GaInAsP/InP material system. Chips were mounted into complete modules and operated in a 1.3 μm/1.55 μm bidirectional transmission link. At 576 Mbit/s and 10−9 bit error rate the sensitivity of the module was −21 dBm, while the intrinsic sensitivity of the receiver was determined to be −28 dBm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107460
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