Temperature dependence of the spin and orbital magnetization density in Sm1−xGdxAl2Sm_{1-x}Gd_{x} Al_{2} around the spin-orbital compensation point

Non-resonant ferromagnetic x-ray diffraction has been used to separate the spin and orbital contribution to the magnetization density of the proposed zero-moment ferromagnet $Sm_{0.982}Gd_{0.018} Al_{2}$. The alignment of the spin and orbital moments relative to the net magnetization shows a sign reversal at 84K, the compensation temperature. Below this temperature the orbital moment is larger than the spin moment, and vice versa above it. This result implies that the compensation mechanism is driven by the different temperature dependencies of the $4f$ spin and orbital moments. Specific heat data indicate that the system remains ferromagnetically ordered throughout

Economic Impact of Bovine Tuberculosis on Minnesota’s Cattle and Beef Sector

Livestock Production/Industries,

Weak coupling d-wave BCS superconductivity and unpaired electrons in overdoped La_{2-x}Sr_{x}CuO_{4} single crystals

The low-temperature specific heat (SH) of overdoped La_{2-x}Sr_{x}CuO_{4} single crystals (0.178=<x=<0.290) has been measured. For the superconducting samples (0.178=<x=<0.238), the derived gap values (without any adjusting parameters) approach closely onto the theoretical prediction \Delta_{0}=2.14k_{B}T_{c} for the weak-coupling d-wave BCS superconductivity. In addition, the residual term \gamma(0) of SH at H=0 increases with x dramatically when beyond x~0.22, and finally evolves into the value of a complete normal metallic state at higher doping levels, indicating growing amount of unpaired electrons. We argue that this large \gamma(0) cannot be simply attributed to the pair breaking induced by the impurity scattering, instead the phase separation is possible.Comment: 6 pages, 6 figures; Contents added; Accepted for publication in Phys. Rev.

High-pressure phases and transitions of the layered alkaline earth nitridosilicates SrSiN2 and BaSiN2

We investigate the high-pressure phase diagram of SrSiN2 and BaSiN2 with density-functional calculation. Searching a manifold of possible candidate structures, we propose new structural modifications of SrSiN2 and BaSiN2 attainable in high-pressure experiments. The monoclinic ground state of SrSiN2 transforms at 3 GPa into an orthorhombic BaSiN2 type. At 14 GPa a CaSiN2-type structure becomes the most stable configuration of SrSiN2. A hitherto unknown Pbcm modification is adopted at 85 GPa and, finally, at 131 GPa a LiFeO2-type structure. The higher homologue BaSiN2 transforms to a CaSiN2 type at 41 GPa and further to a Pbcm modification at 105 GPa. Both systems follow the pressure-coordination rule: the coordination environment of Si increases from tetrahedral through trigonal bipyramidal to octahedral. Some high-pressure phases are related in structure through simple group–subgroup mechanisms, indicating displacive phase transformations with low activation barriers

First evidence for cos2β\u3e0 and resolution of the CKM Unitarity Triangle ambiguity by a time-dependent Dalitz plot analysis of B0→D(∗)h0 with D→K0Sπ+π− decays

We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the CKM Unitarity Triangle using a time-dependent Dalitz plot analysis of B0→D(∗)h0 with D→K0Sπ+π− decays, where h0∈{π0,η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BaBar and Belle experiments collected at the Υ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×106BB¯ pairs recorded by the BaBar detector and (772±11)×106BB¯ pairs recorded by the Belle detector. The results of the measurement are sin2β=0.80±0.14(stat.)±0.06(syst.)±0.03(model) and cos2β=0.91±0.22(stat.)±0.09(syst.)±0.07(model). The result for the direct measurement of the angle β of the CKM Unitarity Triangle is β=(22.5±4.4(stat.)±1.2(syst.)±0.6(model))∘. The quoted model uncertainties are due to the composition of the D0→K0Sπ+π− decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e+e−→cc¯ data sample. CP violation is observed in B0→D(∗)h0 decays at the level of 5.1 standard deviations. The significance for cos2β\u3e0 is 3.7 standard deviations. The trigonometric multifold solution π/2−β=(68.1±0.7)∘ is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle

Ihara's zeta function for periodic graphs and its approximation in the amenable case

In this paper, we give a more direct proof of the results by Clair and Mokhtari-Sharghi on the zeta functions of periodic graphs. In particular, using appropriate operator-algebraic techniques, we establish a determinant formula in this context and examine its consequences for the Ihara zeta function. Moreover, we answer in the affirmative one of the questions raised by Grigorchuk and Zuk. Accordingly, we show that the zeta function of a periodic graph with an amenable group action is the limit of the zeta functions of a suitable sequence of finite subgraphs.Comment: 21 pages, 4 figure

Measurement of cos2β in B0→D(∗)h0 with D→K0Sπ+π− decays by a combined time-dependent Dalitz plot analysis of BaBar and Belle data

We report measurements of sin2β and cos2β from a time-dependent Dalitz plot analysis of B0→D(∗)h0 with D→K0Sπ+π−decays, where the light unflavored and neutral hadron h0 is a π0, η, or ω meson. The analysis is performed with a combination of the final data sets of the \babar\ and Belle experiments containing 471×106 and 772×106 BB¯ pairs collected at the Υ(4S)resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure sin2β=0.80±0.14(stat.)±0.06(syst.)±0.03(model) and cos2β=0.91±0.22(stat.)±0.09(syst.)±0.07(model). The result for the direct measurement of the angle is β=(22.5±4.4(stat.)±1.2(syst.)±0.6(model))∘. The last quoted uncertainties are due to the composition of the D0→K0Sπ+π− decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics e+e−→cc¯ data sample as part of this analysis. We find the first evidence for cos2β\u3e0 at the level of 3.7 standard deviations. The measurement excludes the trigonometric multifold solution π/2−β=(68.1±0.7)∘ at the level of 7.3 standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of β=0∘ is ruled out at the level of 5.1 standard deviations, and thus CP violation is observed in B0→D(∗)h0 decays