Spin and Spin Current -- From Fundamentals to Recent Progresses

Along with the progress of the spin science and spintronics research, the flow of electron spins, \emph{i.e.}, spin current, has come to attract attention. New phenomena and electronic states were explained one after another using the concept of spin current. Moreover, as many of the conventionally known spintronics phenomena became well organized based on spin current it has rapidly been recognized as an essential concept in a wide range of condensed matter physics. In this article, we focus on recent developments in the physics of spin, spin current, and their related phenomena, where the conversion between spin angular momentum and different forms of angular momentum plays an essential role. Starting with an introduction to spin current, we first discuss the recent progress in the spintronic phenomena driven by spin-exchange coupling: spin pumping, topological Hall torque, and emergent inductor. We then extend our discussion to the interaction/interconversion of spins with heat, lattice vibrations, and charge current and address recent progress and perspectives on the spin Seebeck and Peltier effects. Next, we review the interaction between mechanical motion and electron/nuclear spins and argue the difference between the Barnett field and the rotational Doppler effect. We show that the Barnett effect reveals the angular momentum compensation temperature, at which the net angular momentum is quenched in ferrimagnets.Comment: 23 pages, 18 figure

{6,6′-Dimeth­oxy-2,2′-[o-phenyl­enebis(nitrilo­methyl­idyne)]diphenolato}cobalt(II) dichloro­methane disolvate

The title compound, [Co(C22H18N2O4)]·2CH2Cl2, was isolated from the reaction of N,N′(o-phenyl­ene)bis­(vanillalimine) (H2 L) with Co(SCN)2. The crystal structure contains a CoII ion surrounded by the L 2− ligand in a slightly distorted square-planar fashion. Inter­molecular C—H⋯O hydrogen-bonding contacts between the dichloro­methane solvent mol­ecules and the meth­oxy or carboxyl­ate O atoms are observed in the crystal structure. The planar complex mol­ecules stack through inversion related π–π inter­actions between the six-membered rings of the vanillalimine half ligands. The distance between centroids is 3.498 (2) Å and the perpendicular distance is 3.345 Å. A partial stacking is observed with a centroid–centroid distance of 3.830 (2) Å, a perpendicular distance of 3.350 Å and a slippage of 1.856 Å

2,4-Dichloro-6-(8-quinolylamino­methyl­ene)cyclo­hexa-2,4-dien-1-one methanol solvate

The main mol­ecule of the title methanol solvate, C16H10Cl2N2O·CH3OH, exists in the keto form and the C=O and N—H bonds are mutually cis in the crystal structure. The dihedral angle between the quinoline and benzene rings is 11.17 (3)°. A bifurcated intra­molecular N—H⋯(O,N) hydrogen bond is present as well as an O—H⋯O hydrogen bond. In the crystal, C—H⋯O inter­actions link the 3,5-dichloro­salicyl­idene-8-amino­quinoline and methanol mol­ecules

Optimal development of doubly curved surfaces,

Abstract This paper presents algorithms for optimal development (flattening) of a smooth continuous curved surface embedded in three-dimensional space into a planar shape. The development process is modeled by in-plane strain (stretching) from the curved surface to its planar development. The distribution of the appropriate minimum strain field is obtained by solving a constrained nonlinear programming problem. Based on the strain distribution and the coefficients of the first fundamental form of the curved surface, another unconstrained nonlinear programming problem is solved to obtain the optimal developed planar shape. The convergence and complexity properties of our algorithms are analyzed theoretically and numerically. Examples show the effectiveness of the algorithms

Influence of lifestyle choices on risks of CYP1B1 polymorphisms for prostate cancer.

Cytochrome P450 1B1 (CYP1B1) converts xenobiotics to carcinogens and how lifestyle choices may interact with CYP1B1 polymorphisms and affect prostate cancer risk was assessed. Blood genomic DNA from a Caucasian population was analysed at polymorphic sites of the 5' untranslated region of CYP1B1 using TaqMan genotyping assays. Overall, drinker status and minor alleles at rs2551188, rs2567206 and rs10175368 were associated with prostate cancer. Linkage was observed between rs2551188, rs2567206, rs2567207 and rs10175368, and the G-C-T-G haplotype (major allele at respective sites) was decreased in cancer. Interestingly when classified by lifestyle factors, no associations of genotypes were found for non-smokers and non-drinkers, whereas on the contrary, minor type at rs2567206 and rs10175368 increased and major G-C-T-G decreased risk for cancer among smokers and drinkers. Interestingly, rs2551188, rs2567206 and rs10175368 minor genotypes correlated with increased tissue CYP1B1 as determined by immunohistochemistry. Further, rs10175368 enhanced luciferase activity and mobility shift show stronger binding of nuclear factor for the minor allele. These results demonstrate smoking and alcohol consumption to modify the risks of CYP1B1 polymorphisms for prostate cancer which may be through rs10175368, and this is of importance in understanding their role in the pathogenesis and as a biomarker for this disease

GPR52 accelerates fatty acid biosynthesis in a ligand-dependent manner in hepatocytes and in response to excessive fat intake in mice

Gpr52 is an orphan G-protein-coupled receptor of unknown physiological function. We found that Gpr52-deficient (Gpr52−/−) mice exhibit leanness associated with reduced liver weight, decreased hepatic de novo lipogenesis, and enhanced insulin sensitivity. Treatment of the hepatoma cell line HepG2 cells with c11, the synthetic GPR52 agonist, increased fatty acid biosynthesis, and GPR52 knockdown (KD) abolished the lipogenic action of c11. In addition, c11 induced the expressions of lipogenic enzymes (SCD1 and ELOVL6), whereas these inductions were attenuated by GPR52-KD. In contrast, cholesterol biosynthesis was not increased by c11, but its basal level was significantly suppressed by GPR52-KD. High-fat diet (HFD)-induced increase in hepatic expression of Pparg2 and its targets (Scd1 and Elovl6) was absent in Gpr52−/− mice with alleviated hepatosteatosis. Our present study showed that hepatic GPR52 promotes the biosynthesis of fatty acid and cholesterol in a ligand-dependent and a constitutive manner, respectively, and Gpr52 participates in HFD-induced fatty acid synthesis in liver

Strain distribution analysis of sputter-formed strained Si by tip-enhanced Raman spectroscopy

Simultaneous nanometer-scale measurements of the strain and surface undulation distributions of strained Si (s-Si) layers on strain-relief quadruple-Si1-xGex-layer buffers, using a combined atomic force microscopy (AFM) and tip-enhanced Raman spectroscopy (TERS) system, clarify that an s-Si sample formed by our previously proposed sputter epitaxy method has a smoother and more uniformly strained surface than an s-Si sample formed by gas-source molecular beam epitaxy. The TERS analyses suggest that the compositional fluctuation of the underlying Si1-xGex buffer layer is largely related to the weak s-Si strain fluctuation of the sputtered sampl

60 Gbps real-time wireless communications at 300 GHz carrier using a Kerr microcomb

Future wireless communication infrastructure will rely on terahertz systems that can support an increasing demand for large-bandwidth, ultra-fast wireless data transfer. In order to satisfy this demand, compact, low-power, and low noise sources of terahertz radiation are being developed. A promising route to achieving this goal is combining photonic-integrated optical frequency combs with fast photodiodes for difference frequency generation in the THz. Here, we demonstrate wireless communications using a 300 GHz carrier wave generated via photomixing of two optical tones originating from diode lasers that are injection locked to a dissipative Kerr soliton frequency microcomb. We achieve transfer rates of 80 Gbps using homodyne detection and 60 Gbps transmitting simultaneously both data and clock signals in a dual-path wireless link. This experimental demonstration paves a path towards low-noise and integrated photonic millimeter-wave transceivers for future wireless communication systems