arXiv subjects

M. Clovecko

Publications and source records attributed to M. Clovecko.

5 recordsLinked to original sources

arXiv2019

NMR-like effect on Anisotropic Magnetic Moment of Surface Bound States in Topological Superfluid $^3$He-B

We present experimental observation of a new phenomenon, that we interpret as NMR-like effect on anisotropic magnetic moment of the surface Andreev bound states in topological superfluid $^3$He-B at zero temperature limit. We show that an anisotropic magnetic moment formed near the horizontal surface of a mechanical resonator due to symmetry violation of the superfluid $^3$He-B order parameter by the resonator's surface may lead to anomalous damping of the resonator motion in magnetic field. In difference to classical NMR technique, here NMR was excited using own harmonic motion of the mechanical resonator, and nuclear magnetic resonance was detected as a maximum in damping when resonator's angular frequency satisfied the Larmor resonance condition.

cond-mat.other↗

arXiv2018

Spontaneous emergence of van der Waals interaction in piezo-resonators - a road to phase coherence at mK temperatures

We present the experimental results on the spontaneous emergence of the phase coherence in the system of oscillating electric dipoles in quartz piezo-resonators caused by the van der Waals interaction. Spontaneous emergence of the phase coherence in these systems is manifested via temperature-dependent, extremely accurate tune-up of their resonance frequencies in 9th order with relative spectral line-width $δf_0/f_0$ less than 3.10$^{-8}$ (this number is comparable with that in lasers) along with the very high frequency stability characterized by the low values of the Allan deviations. We also show that the application of an incoherent (noise) excitation signal leads to a spontaneous formation of the phase coherent state, and that the dissipation processes do not affect this phase coherent state (i.e. the resonance frequency of the system). All above-mentioned signatures are typical characteristics for a Bose-Einstein condensate of excitations. Smallness of the relative spectral lime-width in quartz piezo-resonators opens their potential application as alternative time etalons.

cond-mat.other↗

arXiv2018

YbPd$_2$In: a promising candidate to strong entropy accumulation at very low temperature

We report on synthesis, crystal structure, magnetic, thermodynamic and transport properties of the new compound YbPd$_2$In, crystallizing as a Heusler structure type. A trivalent state of the rare earth was determined by fitting the magnetic susceptibility with a Curie-Weiss law. This compound is characterized by showing very weak magnetic interactions and a negligible Kondo effect. A specific heat jump was observed at $T\approx 250$ mK, followed at higher temperature by a power law decrease of $C_P(T)/T$. The resulting large electronic entropy increase at very low temperature is rapidly shifted to higher temperature by the application of magnetic field. This magnetocaloric effect places YbPd$_2$In as a very good candidate for adiabatic demagnetization cooling processes.

cond-mat.str-el↗

arXiv2014

Vacuum properties of high quality value tuning fork in high magnetic field up to 8 Tesla and at mK temperatures

Tuning forks are very popular experimental tools widely applied in low and ultra low temperature physics as mechanical resonators and cantilevers in the study of quantum liquids, STM and AFM techniques, etc. As an added benefit, these forks being cooled, have very high Q-value, typically $10^6$ and their properties seems to be magnetic field independent. We present preliminary vacuum measurements of a commercial tuning fork oscillating at frequency 32~kHz conducted in magnetic fields up to 8~T and at temperature $\sim 10$~mK. We found an additional weak damping of the tuning fork motion depending on magnetic field magnitude and we discuss physical nature of the observed phenomena.

cond-mat.mtrl-sci↗

arXiv2006

Quartz Tuning Fork: Thermometer, Pressure- and Viscometer for Helium Liquids

Commercial quartz oscillators of the tuning-fork type with a resonant frequency of ~32 kHz have been investigated in helium liquids. The oscillators are found to have at best Q values in the range 10^5-10^6, when measured in vacuum below 1.5 K. However, the variability is large and for very low temperature operation the sensor has to be preselected. We explore their properties in the regime of linear viscous hydrodynamic response in normal and superfluid 3He and 4He, by comparing measurements to the hydrodynamic model of the sensor.

cond-mat.supr-con↗