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Notes: Spectroscopic ellipsometry measurements have been used as a probe to provide information on the structure of a hydrogenated amorphous silicon based n-i two-layer system. The n-i structure is prepared under the same conditions as an a-Si:H p-i-n cell with a thin (∼150 A(ring)) n layer deposited in a glow discharge from a mixture of SiF4, SiH4, H2, and PH3 on top of intrinsic a-Si:H. An effective medium approximation and a linear regression analysis have been used to determine the bulk microstructure of the thick (0.3 μm) n layer on quartz as a mixture of volume fractions of a-Si (0.74±0.01), c-Si (0.09±0.02), and void (0.17±0.03). When applied to the thin n layer in the solar-cell configuration, however, the corresponding analysis shows evidence of a 100-A(ring) overlayer of very low density a-Si, not observed on the thicker n-type material, which dominates the dielectric properties of the thin layer. These results are suggestive of nucleation and growth surface microstructure on the 150-A(ring) n layer and lead to the conclusion that, in the fabrication of high-performance a-Si:H based devices using thin layers, such structure must be minimized.

Notes: The photorefractive properties of BaTiO3 are gradually modified by the addition of Nb which change the charge carrier from hole to electron. Before the compensation point, the dark conductivity decreases and the response time increases with increasing Nb concentration. Two beam coupling gain can be explained by using the deep and shallow trap model with hole as the major carrier. Near the compensation point, the deep and shallow trap model is needed, in addition to the electron–hole competition to explain this. After the compensation point, an absorption around 600 nm evolves, the dark conductivity increases very fast, and the electron becomes the major carrier. © 1999 American Institute of Physics.

Notes: We report evidence which suggests surface ferromagnetism in a ferromagnetic superconductor arising from the competition between the Meissner current shielding effect and the fluctuations of the localized magnetic moments. We have measured the surface impedance penetration depth Λ of ErRh4B4 and Er0.5Ho0.5Rh4B4 by employing a spectrometer operated at 9 GHz. For ErRh4B4, owing to the critical spin fluctuations just above Ts (〉Tc2), the critical temperature at which surface ferromagnetism appears, Λ−1 decreases smoothly as temperature decreases toward Ts. For Er0.5Ho0.5Rh4B4, the decrease of Λ−1 arising from spin fluctuations for T〉Tc2 is very small, and Λ−1 decreases abruptly at Tc2. We will discuss the theory and show how the predicted values of Λ(T) compare well with the observed values.

Notes: Data on zero-field μSR in ErRh4B4 are presented for temperatures from 4 to 300 K. Due to the large erbium moment, most of the muons have a relaxation time of less than 10 ns for temperatures below about 50 K. The data have been analyzed in terms of two distinct muon sites in the material. The deduced erbium relative fluctuation rate versus temperature is related to the crystalline electric field levels of erbium in the RERh4B4 structure.

Notes: We have investigated two antiferromagnetic superconductors, NdRh4B4 and SmRh4B4, which exhibit two quite different temperature dependencies of the upper critical field arising from two different mechanisms1 of the modification of superconductivity by the presence of antiferromagnetism. In order to further study these mechanisms, we have investigated the electromagnetic properties and have measured the penetration depths λ(T) of NdRh4B4 (Tc=5.45 K, TN1=1.31 K, and TN2=0.89 K) and SmRh4 B4 (Tc=2.2 K, TN=0.9 K), employing a tunnel diode oscillator at ∼30 MHz. Above the antiferromagnetic transition temperature (TN1 for NdRh4B4 and TN for SmRh4B4), the temperature dependencies of the penetration depths of these two superconductors fit the BCS theory well. We have found λ(0)=2170 and 980 A(ring) for NdRh4B4 and SmRh4B4, respectively. However, as temperature is lowered, λ(T) for NdRh4B4 increases near TN1 and then saturates near TN2, presumably owing to the molecular field effect.2 The spin-fluctuation effects,2 expected to be significant near TN2 for NdRh4B4 and TN for SmRh4B4, have not been observed within our experimental accuracy.

Notes: The use of polymer-dispersed liquid crystal films to fabricate gratings was demonstrated. The written gratings are permanent, but are electrically switchable. In this article, we report the results obtained from the dynamical studies of gratings formed in polymer-dispersed liquid crystal films having various liquid crystal-polymer mixing ratios. The results showed that during the initial phases of formation, a thermal grating effect dominated. Later, it was offset or quenched by the photopolymerization effect which eventually dominated and determined the characteristics of the final grating. © 1998 American Institute of Physics.

Notes: We report that in BaTiO3:Rh the carrier-type depends not only on the postprocessing condition but also on the incident wavelength in two beam coupling. Carriers are the holes for the as-grown sample, and change to electrons for the sample reduced in the atmosphere of 10−14 atm oxygen partial pressure. However, for the sample reduced in the atmosphere of 10−10 atm oxygen partial pressure, the carrier is an electron for the incident wavelength of 514 nm, and a hole for 633 nm. Its absorption, photoinduced absorption, and two beam coupling are investigated and discussed. © 1998 American Institute of Physics.

Notes: High quality Y3Fe5O12/Gd3Ga5O12 (YIG/GGG) superlattices have been grown on (111)GGG substrates by pulsed laser deposition. The superlattices are investigated with the thickness of the YIG layer varied from six to one unit cells while keeping the GGG layer fixed at one unit cell. The thicknesses of the YIG and GGG layers are confirmed with grazing angle x-ray reflectivity (GAXR). The good quality of the samples is indicated by the small interface roughness, no more than 6 A(ring), also measured with GAXR. While the magnetization of the samples decreases when the thickness of the YIG layer is decreased, the superlattice remains magnetic even when the YIG layer is only one unit cell. Ferrimagnetic resonance indicates that there exists a surface anisotropy favoring in-plane magnetization. © 1996 American Institute of Physics.

Notes: Background Primary cutaneous amyloidoses are rare in Western countries, but are relatively common in Taiwan. Anosacral cutaneous amyloidosis is a rare type of primary cutaneous amyloidoses, first reported in Japanese patients. Patients/methods In the present study, we investigated the age of onset, sites of involvement, associated systemic diseases, and histopathological findings in 10 cases of anosacral cutaneous amyloidosis seen during the past 27 years. Results In previous reports the aetiology of anosacral cutaneous amyloidosis was thought to be a senile change, but half of our patients developed the disease before the age of 60 years. Based on our histopathological findings, apoptosis may be the initial event causing amyloid deposition, although the precise mechanism causing apoptosis needs further investigation. Three patients were found to have diabetes mellitus, but any relationship to anosacral cutaneous amyloidosis is unclear. Conclusions No cases of this cutaneous disorder have been reported in the Western literature; there seems to be a racial difference accounting for the disease, although the precise factor is not clarified yet. The disease could easily be misdiagnosed as lichen simplex chronicus, postinflammatory hyperpigmentation or tinea cruris; therefore, a thorough history, a careful physical examination and a skin biopsy is needed to establish a firm diagnosis.

Notes: Background  There is a high incidence of primary cutaneous amyloidosis (PCA) in South America, South-east Asia and Taiwan. To date, the aetiology of PCA remains unknown, but it is believed to be multifactorial. Although most cases are sporadic, some patients have a family history. Familial aggregation and different susceptibility to PCA among ethnic groups suggest that genetic factors may play an important role in its pathogenesis. However, no genetic loci for familial PCA (FPCA) have been identified so far.Objectives  In order to identify the susceptibility gene of FPCA, we took a candidate gene approach and performed linkage analysis on chromosome 1q21.3–24.2, including the 1q23.2 region where the gene encoding serum amyloid P component (APCS) is located.Patients and methods  Nine FPCA families including 29 individuals affected with PCA were recruited for this linkage study. Initially, 11 highly polymorphic microsatellite markers spanning the region from 1q21.3 to 1q24.2 were genotyped and revealed a suggestive linkage region. This region was further fine-mapped with seven additional markers. We also re-sequenced the 2·5-kb genomic region of the APCS gene in 29 affected and 42 control individuals. Two-point and multipoint linkage analyses were performed using the LINKAGE program. Nonparametric linkage (NPL) analysis and reconstruction of haplotypes were performed with the GENEHUNTER program.Results  Both two-point and multipoint linkage analysis for all 11 markers generated negative or small positive total lod scores for all nine families. However, when we considered only three families, a maximum two-point total lod score of 2·09 was obtained for the marker D1S2844 at θ = 0·01. A plateau of multipoint total lod score between D1S2768 and D1S2878 with a maximum of 2·48 at the marker D1S2844 was observed. A maximum NPL score of 3·11 (P = 0·008) was also obtained for the marker D1S2878. However, re-sequencing of the APCS gene identified no functional mutation.Conclusions  Both parametric and nonparametric linkage evidence suggested that a possible susceptibility locus for a subset of FPCA might exist on chromosome 1q23. This is the first report demonstrating suggestive evidence of linkage of FPCA to a locus in this candidate region. No functional sequence variations of the APCS gene were found to be associated with this disease among the study families. Our data imply the existence of at least one additional locus responsible for FPCA in these families, confirming genetic heterogeneity of this skin disorder.