摘要:

An experimental study of magnetization process for CeC2crystals encapsulated in carbon nanocages in the low‐temperature antiferromagnetic region (T<30 K) in steady magnetic fields up to 15 T is reported. The magnetization curves show a dramatic change at a critical fieldHc∼3.5 T. At a particular fieldHs(<12±1 T), net magnetization levels off. The behavior atHcis ascribed to a phase transition between an antiferromagnetic and a spin‐flop state, and that atHsto a phase transition between the spin‐flop and a paramagnetic state. The magnetic phase diagram in the applied field and temperature plane is accurately determined based on the results ofHc(T) andHs(T). ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115655

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The crystal structure and magnetic properties of a LaCo10Al3intermetallic compound have been investigated by x‐ray powder diffraction and magnetic measurement. The space group of the LaCo10Al3structure isI4/mcm, which can be derived from the cubic NaZn13‐type structure. Each unit cell contains four formula units of LaCo10Al3. The lattice parameters area=8.085(1) A˚,c=11.624(8) A˚, and the calculated density isDx=7.07(3) g/cm3. In each unit cell, there are five kinds of equivalent positions, i.e., 4a, 16l(1), 16k16l(2), and 4d, which are occupied by 4La, 16Co(1), 16Co(2), 16(Co+Al) and 4Co(3)atoms, respectively. The tetragonal LaCo10Al3intermetallic compound is ferromagnetic with a Curie temperature of 840 K. The magnetic moment per Co atom is 0.84&mgr;B, which can be explained by the magnetic valence model. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115656

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We present a theoretical approach to study the dielectric properties of porous ceramics and composite materials and explain the experimentally observed notable influence of the coupling between the components of a saturated porous ceramic on the final behavior of the sample. This model is based on the assumption of a dielectric coupling between the components that modifies the expected averaged properties of the material. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115657

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We use Fowler–Nordheim tunneling current oscillations to accurately determine the thicknesses of ultrathin SiO2films, and with the thicknesses as input, we employ precision single wavelength ellipsometry to determine the real part of the refractive index for thin SiO2films in the range of 4–6 nm. An average value for this refractive index was found to be 1.894±0.110. This value is shown to yield SiO2thicknesses to an accuracy of ±0.1 nm. A SiO2thickness‐refractive index interpolation formula for the thin film regime is given. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115658

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Charge distributions in thermally poled silica glass are mapped by using laser induced pressure pulse technique. The experimental results may be explained through postulating the formation of both real space charge layers and dipole polarization inside the depletion region. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115659

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The effect of crystallization temperature on the electrical properties of sol‐gel derived Pb(Zr,Ti,Nb)O3or PNZT capacitors with La0.5Sr0.5CoO3(LSCO) electrodes has been investigated. It is demonstrated that LSCO//PNZT(4/30/70)//LSCO capacitors can be fabricated at temperatures as low as 550 °C without significant degradation in their ferroelectric and dielectric properties. Lowering the process temperature to 500 °C resulted in substantial degradation in capacitor properties. Nonetheless, all capacitors processed in the 500 °C to 675 °C range exhibited essentially no fatigue up to 5×109switching cycles. The low temperature processing is significant as it indicates that this ferroelectric capacitor technology is compatible with high density nonvolatile memory architectures. In other words, these process temperatures are low enough to maintain plug integrity and to prevent degradation of the underlying CMOS circuitry in a high density ferroelectric memory. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115660

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have developed a method, anodization controlled miniaturization enhancement (ACME), to make ultrasmall tunnel junctions. Anodization of electron‐beam fabricated Al/Al2O3/Al tunnel junctions reduces their effective areas and capacitances, which realizes single electron transistors operating at high temperatures up to nearly 30 K. The limit of the increase in the charging energy is attributed to the initial scattering in the junction sizes. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115661

出版商:AIP    

年代:1996

数据来源: AIP