1,439 research outputs found

    Antiferromagnetic and Orbital Ordering on a Diamond Lattice Near Quantum Criticality

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    We present neutron scattering measurements on powder samples of the spinel FeSc2S4 that reveal a previously unobserved magnetic ordering transition occurring at 11.8(2)~K. Magnetic ordering occurs subsequent to a subtle cubic-to-tetragonal structural transition which distorts Fe coordinating sulfur tetrahedra lifting the orbital degeneracy. The application of 1~GPa hydrostatic pressure appears to destabilize this N\'eel state, reducing the transition temperature to 8.6(8)~K and redistributing magnetic spectral weight to higher energies. The relative magnitudes of ordered m2 ⁣= ⁣3.1(2)\langle m \rangle^2\!=\!3.1(2) and fluctuating moments δm2 ⁣= ⁣13(1)\langle \delta m \rangle^2\!=\!13(1) show that the magnetically ordered ground state of FeSc2S4 is drastically renormalized and in proximity to criticality.Comment: 16 pages, 12 figure

    Failure of systemic ketosis to control cachexia and the growth rate of the Walker 256 carcinosarcoma in rats.

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    The Walker 256 carcinosarcoma was shown to lack the enzyme 3-ketoacid CoA transferase. This suggests that ketone bodies cannot be used as a major substrate for the energy metabolism of this tumour. Systemic ketosis (1-2 mM acetoacetate plus 3-hydroxybutyrate) was induced both in tumour-bearing and in non-tumour-bearing rats with a diet containing 70% medium chain triglyceride. However, in rats bearing the Walker 256 tumour, this dietary ketosis did not reduce the tumour growth rate nor did it prevent the subsequent decrease in host body weight. Host body nitrogen losses were similarly unaffected. The ketosis induced in tumour bearing rats was shown to be abnormal since the blood glucose concentration of ketotic, tumour-bearing rats was significantly higher compared with that of ketotic non-tumour bearing rats (5.2 +/- 0.4 mM cf 3.4 +/- 0.6 mM, P less than 0.01). These results may partly explain why systemic ketosis failed to alter the growth and cachexia induced by the Walker 256 carcinosarcoma

    Single spin-polarised Fermi surface in SrTiO3_3 thin films

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    The 2D electron gas (2DEG) formed at the surface of SrTiO3_3(001) has attracted great interest because of its fascinating physical properties and potential as a novel electronic platform, but up to now has eluded a comprehensible way to tune its properties. Using angle-resolved photoemission spectroscopy with and without spin detection we here show that the band filling can be controlled by growing thin SrTiO3_3 films on Nb doped SrTiO3_3(001) substrates. This results in a single spin-polarised 2D Fermi surface, which bears potential as platform for Majorana physics. Based on our results it can furthermore be concluded that the 2DEG does not extend more than 2 unit cells into the film and that its properties depend on the amount of SrOx_x at the surface and possibly the dielectric response of the system

    Evolution from a nodeless gap to d(x2-y2) form in underdoped La(2-x)SrxCuO4

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    Using angle-resolved photoemission (ARPES), it is revealed that the low-energy electronic excitation spectra of highly underdoped superconducting and non-superconducting La(2-x)SrxCuO4 cuprates are gapped along the entire underlying Fermi surface at low temperatures. We show how the gap function evolves to a d(x2-y2) form as increasing temperature or doping, consistent with the vast majority of ARPES studies of cuprates. Our results provide essential information for uncovering the symmetry of the order parameter(s) in strongly underdoped cuprates, which is a prerequisite for understanding the pairing mechanism and how superconductivity emerges from a Mott insulator.Comment: 5 pages, 4 figure
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