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LTLT
At the moment this page is under construction. I'm changing it and trying to understand how to organize information.
I was working in V.Dmitriev's group. My personal master project was to rebuild a small dilution fridge, use it for measuring transition-edge bolometers for another group, and add a 4He circulation loop to the fridge. Two first tasks were successful, the last one did not give any noteceable improvement, probably because of my lack of experience. Then I joined the main group working on NMR in superfluid $^3$He. We mostly studied superfluid phases in isotropic aerogel, but also oscillation modes of HPD state. This was topic of my PhD work finished in 2011.
Nonlinear NMR in a superfluid B phase of 3He in aerogel V.V.Dmitriev, V.V.Zavjalov, D.E.Zmeev, I.V.Kosarev, N.Mulders, Jetp Lett. 76, 312-317 (2002) [DOI] [pdf] [bib] [pdf:ru] [bib:ru]
Superfluid phases of 3He in aerogel V.V.Dmitriev, V.V.Zavjalov, D.E.Zmeev, I.V.Kosarev, N.Mulders, Physics-Uspekhi, 46, 438 (2003) [DOI] [pdf] [bib] [pdf:ru] [bib:ru]
Pulsed NMR experiments in superfluid confined in aerogel V.V.Dmitriev, I.V.Kosarev, N.Mulders, V.V.Zavjalov, D.Ye.Zmeev, Physica B: Cond.Mat. 329-333, 296-298 (2003) [DOI] [pdf] [bib]
Experiments on A-like to B phase transitions of 3He confined to aerogel V.V.Dmitriev, I.V.Kosarev, N.Mulders, V.V.Zavjalov, D.Ye.Zmeev, Physica B: Cond.Mat. 329-333, 320-321 (2003) [DOI]
Measurements of longitudinal and transverse magnetic relaxation in superfluid confined to aerogel V.V.Dmitriev, I.V.Kosarev, N.Mulders, V.V.Zavjalov, D.Ye.Zmeev, Physica B: Cond.Mat. 329-333, 322-323 (2003) [DOI] [pdf] [bib]
Homogeneous spin precession in superfluid confined to aerogel V.V.Dmitriev, I.V.Kosarev, N.Mulders, V.V.Zavjalov, D.Ye.Zmeev, Physica B: Cond.Mat. 329-333, 324-326 (2003) [DOI] [pdf] [bib]
Measurement of the Leggett frequency in 3He-B in aerogel V.V.Dmitriev, V.V.Zavjalov, D.Y.Zmeev, N.Mulders, Jetp Lett. 79, 499-503 (2004) [DOI]
Spatially homogeneous oscillations of homogeneously precessing domain in 3He-B V.V.Dmitriev, V.V.Zavjalov, D.Y.Zmeev, J Low Temp Phys 138, 765770 (2005) [DOI]
Purification of 3He from a 4He Impurity Using Adsorption V. V. Dmitriev, V. V. Zavjalov, D. Ye. Zmeev & L. V. Levitin, Instr.and Exp.Tech., 47, 567-569, (2004) [DOI] [pdf] [bib]
I was working in V.Eltsov's group from May 2012 until December 2015. First I joined their big and successful experiment with trapped magnons in $^3$He-B in the rotating cryostat. An accurate harmonic trap was formed in a long cylindrical cell by $^3$He texture and magnetic field. We were able to populate individual levels in the trap and do precision spectroscopy; observe bose-condensation of magnons, modification of the trapping potential by the condensate (self-trapping), parammetric instability with creation of longitudinal and acoustic magnons, interaction of the condensate with vortices and free surface.
In 2015 the experiment in the rotating cryostat has been changed. We put a plastic cell with aerogel sample, obtained polar phase in $^3$He in aerogel, observed and studied half-quantum vortices in it. I was not involved that much in the experiment, but did theoretical and numerical calculations of half-quantum vortices, textures, and spin waves in the polar phase (thanks to G. Volovik for guidance and support).
Relaxation of Bose-Einstein Condensates of Magnons in Magneto-Textural Traps in Superfluid 3He-B P.J.Heikkinen, S.Autti, V.B.Eltsov, J.J.Hosio, M.Krusius, V.V.Zavjalov, J Low Temp Phys 175, 316 (2014) [DOI]
Microkelvin Thermometry with Bose-Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid He P.J.Heikkinen, S.Autti, V.B.Eltsov, R.P.Haley, V.V.Zavjalov, J Low Temp Phys 175, 681705 (2014) [DOI]
Measurements of the anisotropic mass of magnons confined in a harmonic trap in superfluid 3He-B V.V.Zavjalov, S.Autti, V.B.Eltsov, P.J.Heikkinen, Jetp Lett. 101, 802807 (2015) [DOI]
Light Higgs channel of the resonant decay of magnon condensate in superfluid 3He-B V.V.Zavjalov, S.Autti, V.B.Eltsov, P.J.Heikkinen, G.E.Volovik, Nat. Commun. 7:10294 (2016) [DOI]
Propagation of self-localized -ball solitons in the 3He universe S.Autti, P.J.Heikkinen, G.E.Volovik, V.V.Zavjalov, V.B.Eltsov, Phys. Rev. B 97, 014518 (2018) [DOI]
Observation of Half-Quantum Vortices in Topological Superfluid 3He S.Autti, V.V.Dmitriev, J.T.Mäkinen, A.A.Soldatov, G.E.Volovik, A.N.Yudin, V.V.Zavjalov, V.B.Eltsov, Phys. Rev. Lett. 117, 255301 (2016) [DOI]
Linear NMR in the Polar Phase of 3He in Aerogel V.V.Zavjalov, Jetp Lett. 108, 402-408 (2018) [DOI]
I was working in P. Hakonen's group from May 2016 until May 2019. My main project was to design and build a complicated experiment with NMR in superfluid $^3$He-B where a few volumes of HPD coherent precession are separated by graphene membranes. The plan was to study coupling of superfluid spin currents through the membranes. My first idea was to arrange a simpler experiment with only one HPD volume, to build and test NMR coil system, spectrometer, and other components for the main experiment. Unfortunately it was very difficult to get access to the demagnetization cryostat. I was doing a lot of side projects while waiting for it, the most useful was designing a building HEMT-based cold amplifiers (a few tens of them were produced by me in the lab, and in collaboration with Aivon company) [paper].
I obtained access to the cryostat only in the beginning of 2018, put the simple cell in it, and in June we had about a month of quite successful measurements. The experiment was quick and not very accurate, but we have found really pazzling oscillation modes in HPD. After many attempts to understand them, in 2023 we came to a conlusion that it is oscillations of theta-solitons in HPD and managed to support this result with numerical simulations [paper].
Unfortunately after the short period of measurements the cryostat was not available again. Only in the beginning of 2019 we got access to uKI cryostat, a very good wet fridge. Together with E.Sergeicheva who joined the group in 2018 we finished the cell with three HPD volumes separated by graphene membranes and installed it into the fridge. But I already decided to leave the lab.
In Lancaster I was making a big experiment on thermal properties of superfluid $^3$He surfaces, together with D.Zmeev. During the first year the experimental cell was constructed and lots of improvements of the cryostat and measurement systems were made (new cryostat wiring, rebuilding of the mixture-hanling system, new device rack and software system for full remote control of the cryostat and 15-channel vibrating wire measurement). For this project I organized a home workshop where I was able to machine most of needed parts during the covid lookdown.
The second year passed in fights with leaks and other problems. A successful experiment started in March 2022 and finished in July 2022 with explosion of the cell (mixing chamber and radiation shield were also broken). After rebuilding the cell, fixing the cryostat, and cleaning $^3$He sample I restarted the experiment in November 2022 and run it almost continously until Jan 2024, collecting lots of interesting data. I was also collecting data on random heating events in superfluid bolometers for QUEST DMC project. Unfortunately I had to leave UK due to visa problems in March 2024.
Most of my code is under GPL v3.0 License. Most packages contain spec file for Altlinux (it's my main packaging system), some have files for building packages for Gentoo (thanks to A.S.) and Ubuntu.