This paper reviews spin-transfer magnetization switching in ordered alloy-based nanopillar devices. L1
0
-ordered FePt was used for one of the earliest demonstrations of spin-transfer switching in ...perpendicularly magnetized systems. The behaviour of magnetization switching deviates from the predictions based on a macro-spin model, suggesting incoherent magnetization switching in the system with a large perpendicular magnetic anisotropy. The effect of a 90° spin injector on spin-transfer switching was also examined using L1
0
-ordered FePt. Full-Heusler alloys are in another fascinating material class for spin-transfer switching because of their high-spin polarization of conduction electrons and possible small magnetization damping. A B2-ordered Co
2
FeAl
0.5
Si
0.5
-based device showed a low intrinsic critical current density of 9.3 × 10
6
A cm
−2
for spin-transfer switching as well as a relatively large current-perpendicular-to-plane giant-magnetoresistance (CPP-GMR) up to ∼9%. The specific physical properties of ordered alloys may be useful for fundamental studies and applications in spin-transfer switching.
Fermi level tuning has been successfully demonstrated in Co-based full-Heusler alloy Co(2)FeAl(0.5)Si(0.5) (CFAS). The half-metallic band gap of CFAS was proved by the behavior of differential ...conductance of CFAS/(MgAl(2))O(x)/CoFe magnetic tunneling junctions with an unexplored crystalline (MgAl(2))O(x) barrier. CFAS exhibits the highest effective spin polarization (P_{eff}) at 300 K and the weakest temperature dependence of P_{eff} among all known half metals. Further study shows that P_{eff} of CFAS decays with increasing temperature (T) following T;{3/2} law perfectly, which indicates that the depolarization of CFAS is determined by spin wave excitation only.
EVI1 and MEL1 are homolog genes whose transcriptional activations by chromosomal translocations are known in small subsets of leukemia. From gene expression profiling data of 130 Japanese pediatric ...acute myeloid leukemia (AML) patients, we found that EVI1 and MEL1 were overexpressed in ~30% of patients without obvious translocations of these gene loci, and that their high expression was significantly associated with inferior survival. High EVI1 expression was detected mainly in myelomonocytic-lineage (designated as e-M4/M5 subtype) leukemia with MLL rearrangements and in megakaryocytic-lineage (designated as e-M7 subtype) leukemia, and its prognostic association was observed in the e-M4/M5 subtype but not in the e-M7 subtype. On the other hand, high MEL1 expression was detected in myelocytic-lineage (designated as e-M0/M1/M2 subtype) and e-M4/M5 subtype leukemia without MLL rearrangements, and its prognostic association was independent from the subtypes. Because of their subtype-dependent and mutually exclusive expression, a combined evaluation of their high expression enabled a clear distinction of patients with inferior survival (P<0.00001 in event-free survival (EFS) and overall survival (OS)). This association was confirmed by quantitative reverse transcription PCR analysis of an independent cohort of 81 patients (P=0.00017 in EFS, P=0.00028 in OS). We propose that the combined estimation of EVI1 and MEL1 expression will be an effective method to predict the prognosis of pediatric AML.
The stress-induced resistance drift in MgO-based magnetic tunnel junctions (MTJs) with Mg insertion layer above and below a MgO tunnel barrier is investigated. Mg insertion suppresses the resistance ...drift. Resistance drift characteristics are improved when electrons tunnel into the Mg-inserted barrier–electrode interface, indicating that Mg insertion significantly suppresses trap site formation at the anode-side barrier–electrode interface. However, transmission electron microscopy images confirm that there is little difference in interface crystallinity between the Mg-inserted and non-inserted interfaces. Therefore, it is shown that a slight modification of the barrier–electrode interface states has a significant impact on resistance drift characteristics, and Mg insertion on both interface sides appears to be an effective way to improve MTJ device reliability in practical applications.
BTBD10, an Akt interactor, activates Akt by decreasing the protein phosphatase 2A-mediated dephosphorylation and inactivation of Akt. Overexpression of BTBD10 suppresses motor neuron death that is ...induced by a familial amyotrophic lateral sclerosis (ALS)-linked superoxide dismutase 1 (SOD1) mutant, G93A-SOD1 in vitro. In this study, we further investigated the BTBD10-mediated suppression of motor neuron death. We found that the small interfering RNA-mediated inhibition of BTBD10 expression led to the death of cultured motor neurons. In Caenorhabditis elegans (C. elegans), disruption of the btbd-10 gene caused not only loss of neurons, including both motor and touch-receptor neurons, but also a locomotion defect. In addition, we found that the expression of BTBD10 was generally decreased in the motor neurons from patients of sporadic ALS and transgenic mice overexpressing G93A-SOD1 (G93A-SOD1-transgenic mice). Collectively, these results suggest that the reduced expression of BTBD10 leads to motor neuron death both in vitro and in vivo.
The p53 tumor suppressor promotes apoptosis in response to DNA damage. Here we describe the Caenorhabditis elegans gene ced-13, which encodes a conserved BH3-only protein. We show that ced-13 mRNA ...accumulates following DNA damage, and that this accumulation is dependent on an intact C. elegans cep-1/p53 gene. We demonstrate that CED-13 protein physically interacts with the antiapoptotic Bcl-2-related protein CED-9. Furthermore, overexpression of ced-13 in somatic cells leads to the death of cells that normally survive, and this death requires the core apoptotic pathway of C. elegans. Recent studies have implicated two BH3-only proteins, Noxa and PUMA, in p53-induced apoptosis in mammals. Our studies suggest that in addition to the BH3-only protein EGL-1, CED-13 might also promote apoptosis in the C. elegans germ line in response to p53 activation. We propose that an evolutionarily conserved pathway exists in which p53 promotes cell death by inducing expression of two BH3-only genes.
Alternate monatomic layer (ML) deposition technique has been used to fabricate a metastable L10-ordered phase of FeNi alloys. The films were prepared by alternating Fe (001) and Ni (001) MLs on MgO ...(001) substrates at various temperatures TS in the range between 80 and 400 deg C. It has been found that the degree of long-range order S evaluated by X-ray diffraction increases with TS, and it has a maximum at TS=240 deg C. With further increase of TS, S shows a drastic decrease, and almost disappears at TS=280 deg C. 280 deg C is close to the order-disorder transformation temperature in the thermal equilibrium. The variation of Ku shows the same tendency as that of S, suggesting the formation of L10-ordered FeNi alloy in the range of TS=200-260 deg C. Maximum values of S=0.6+/-0.2 and Ku=6.3X106(erg/cm3) are obtained at TS=240 deg C. Keyword: L10-ordered structure; Fe-Ni alloy; Uniaxial magnetic anisotropy; Thin film;Metastable structure PACS classification codes: 61.14.-x; 68.55.-a; 75.30.Gw; 75.70.Ak
Specimen-size effect and notch-size effect on the tensile strength of woven fabric carbon/epoxy laminates are evaluated and modeled. For two different layups of (0/90)
12
and (±45)
2
/(0/90)
5
S
, ...respectively, static tension tests were performed on two-dimensional geometrically similar unnotched and double-edge notched specimens scaled to three different sizes. Experimental results demonstrate that the notched strength of the woven CFRP laminates depend on the size of specimen as well as the size of notch. The ratio of notched strength to unnotched strength decreases as the length of notch increases, regardless of the size of specimen. For a given size of notch, the notch strength ratio becomes larger with decreasing size of specimen. A notch-size effect law is derived by means of the Neuber interpolation method. A specimen-size effect is embedded into the notch sensitivity parameter involved by the notch-size effect law to establish a size effect law that can cope with these two kinds of size effect. The engineering size effect law proposed can adequately describe the specimen-size effect as well as notch-size effect on the tensile strength of the woven CFRP laminates. It is also demonstrated that the size effect law allows determining the size independent fracture toughness on the basis of notched strengths of small specimens that fail in a quasi-brittle manner.
This work reports on the fabrication of thin films of inorganic thermoelectric materials like borides, germanides, manganese compounds, and characterization of their thermoelectric properties. We ...have utilized a unique high temperature molecular beam epitaxy (MBE) apparatus to grow hexaboride thin films and manganese germanides. Magnetic manganese based alloy thin films were also grown using sputtering, since we are interested in the possibilities of utilizing magnetism to develop thermoelectric materials.
MgAl2O4 (MAO)-based magnetic tunnel junctions (MTJs) with an MAO thickness of ∼1.25 nm are fabricated and their cycling characteristics under dynamic voltage stress are evaluated. The speed of ...breakdown strongly depended on the pulse polarities used, bipolar, positive (+) unipolar, and negative (−) unipolar. The bipolar condition yielded more rapid breakdown under cycling. Between the two unipolar conditions, positive bias yielded more rapid breakdown than negative bias; the difference between these is understood to arise from the conditions of the interface between the MAO and ferromagnetic layers. Among apparently normal MTJ cells showing little resistance drift, 20% were degraded during a long cycling test in the bipolar stress condition. Thus, the use of bipolar voltage stress is essential to screen for potentially defective MTJs, and the asymmetric condition at the interface is minimised by process control for application of the simple unipolar bias condition.
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