Electronic thermal transport measurement in low-dimensional materials with graphene non-local noise thermometry.

In low-dimensional systems, the combination of reduced dimensionality, strong interactions and topology has led to a growing number of many-body quantum phenomena. Thermal transport, which is sensitive to all energy-carrying degrees of freedom, provides a discriminating probe of emergent excitations in quantum materials and devices. However, thermal transport measurements in low dimensions are dominated by the phonon contribution of the lattice, requiring an experimental approach to isolate the electronic thermal conductance.

High-bandwidth, variable-resistance differential noise thermometry.

We have developed Johnson noise thermometry applicable to mesoscopic devices with variable source impedance with high bandwidth for fast data acquisition. By implementing differential noise measurement and two-stage impedance matching, we demonstrate noise measurement in the frequency range of 120 MHz-250 MHz with a wide sample resistance range of 30 Ω-100 kΩ tuned by gate voltages and temperature. We employed high-frequency, single-ended low noise amplifiers maintained at a constant cryogenic temperature in order to maintain the desired low noise temperature.

Search for supersolidity in solid 4He using multiple-mode torsional oscillators.

In 2004, Kim and Chan (KC) reported a decrease in the period of torsional oscillators (TO) containing samples of solid (4)He, as the temperature was lowered below 0.2 K [Kim E, Chan MHW (2004) Science 305(5692):1941-1944]. These unexpected results constituted the first experimental evidence that the long-predicted supersolid state of solid (4)He may exist in nature.

Control of the iridium oxidation state in the hollandite iridate solid solution K(1-x)Ir4O8.

The synthesis and physical properties of the K(1-x)Ir4O8 (0 ≤ x ≤ 0.7) solid solution are reported. The structure of KIr4O8, solved with single-crystal X-ray diffraction at T = 110 K, is found to be tetragonal, space group I4/m, with a = 10.

[Effect of low temperature on the resistance and functional activity of the photosynthetic apparatus of wheat plants].

The dynamics of cold resistance and the activity of the photosynthetic apparatus (PSA) of wheat germs at 4 degrees C were studied. It was shown that in the first hours of cold, a certain functional readjustment to the changed conditions takes place in the plant organism. A decrease in the activity of the PSA and cessation of the linear growth of the leaf are registered at this stage along with an increase in resistance, as well as an increase in the coefficient of nonphotochemical extinguishing of the fluorescence of chlorophyll.