Proc Natl Acad Sci U S A
December 2022
We report that high-quality single crystals of the hexagonal heavy fermion material uranium diauride (UAu) become superconducting at pressures above 3.2 GPa, the pressure at which an unusual antiferromagnetic state is suppressed. The antiferromagnetic state hosts a marginal fermi liquid and the pressure evolution of the resistivity within this state is found to be very different from that approaching a standard quantum phase transition.
View Article and Find Full Text PDFThe thermoelectric performance of ACuP (A = Mg and Ca) with abundant elements and low gravimetric density is reported. Both systems are p-type doped by intrinsic Cu vacancy defects, have large power factors and promising figures of merit, reaching = 0.5 at 800 K.
View Article and Find Full Text PDFThe term Fermi liquid is almost synonymous with the metallic state. The association is known to break down at quantum critical points (QCPs), but these require precise values of tuning parameters, such as pressure and applied magnetic field, to exactly suppress a continuous phase transition temperature to the absolute zero. Three-dimensional non-Fermi liquid states, apart from superconductivity, that are unshackled from a QCP are much rarer and are not currently well understood.
View Article and Find Full Text PDFThe theory of quantum order-by-disorder (QOBD) explains the formation of modulated magnetic states at the boundary between ferromagnetism and paramagnetism in zero field. PrPtAl has been argued to provide an archetype for this. Here, we report the phase diagram in magnetic field, applied along both the easy a axis and hard b axis.
View Article and Find Full Text PDFA better understanding of the synthesis conditions, composition and physical properties of UTeare required to interpret previously reported unconventional superconductivity. Here we report how the superconducting properties of single crystals depend on the ratio of elements present in their synthesis by chemical vapour transport. We have obtained crystals with the highest reported ambient pressureand a larger superconducting heat capacity jump from a growth with a U:Te ratio different from that widely used in the literature.
View Article and Find Full Text PDFAlthough CCD X-ray detectors can be faster to use, their large-area versions can be much more expensive than similarly sized photographic plate detectors. When indexing X-ray diffraction patterns, large-area detectors can prove very advantageous as they provide more spots, which makes fitting an orientation easier. On the other hand, when looking for single crystals in a polycrystalline sample, the speed of CCD detectors is more useful.
View Article and Find Full Text PDFWe have developed a miniature diamond anvil cell for magnetization measurements in a widely used magnetic property measurement system commercial magnetometer built around a superconducting quantum interference device. The design of the pressure cell is based on the turnbuckle principle in which force can be created and maintained by rotating the body of the device while restricting the counterthreaded end-nuts to translational movement. The load on the opposed diamond anvils and the sample between them is generated using a hydraulic press.
View Article and Find Full Text PDFNew TbFeAs(O,F) and DyFeAs(O,F) superconductors with critical temperatures T(c) = 46 and 45 K and very high critical fields, >or=100 T, have been prepared at 1100-1150 degrees C and 10-12 GPa, demonstrating that high pressure may be used to synthesise late rare earth derivatives of the recently reported RFeAs(O,F) (R = La-Nd, Sm, Gd) high temperature superconductors.
View Article and Find Full Text PDFDavid Hill followed his father, A.V. Hill FRS, into the study of muscular contraction.
View Article and Find Full Text PDFIn 1939, A.L. Hodgkin and I found that the nerve action potential shows an "overshoot"--that is, the interior of the fibre becomes electrically positive during an action potential.
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