Moscow Institute of Physics and Technology

Theoretical nanophysics laboratory (laboratory is closed since 31.12.2016)

Upcoming quantum-nanophysics seminars
Scientific Council of the Landau Institute, Friday, January 18, 2019, Landau Institute, 11:30 am

P.D. Grigoriev, A.D. Grigoriev, A.M. Dyugaev

Inelastic neutron scattering as a confirmation of a new type of gapped surface excitations in liquid helium

We analyze the experimental data on inelastic neutron scattering by a thin ~5-atomic-layer film of liquid helium at three different temperatures: T=0.4K, 0.98K and 1.3K. The neutron scattering intensity plots, in addition to the previously know dispersion of phonons and ripplons, suggest a branch of gapped surface excitations with activation energy ~4.5K and the dispersion similar to that expected for surfons -- the bound quantum states of helium atoms above liquid helium surface, proposed and investigated theoretically. These data, probably, provide the first direct experimental confirmation of surfons. Before these surface excitations received only indirect experimental substantiation, based on the temperature dependence of surface tension coefficient and on their interaction with surface electrons. The existence of surfons as an additional type of surface excitations, although being debated yet, is very important for various physical properties of He surface. We also analyze previous numerical results on excitations in liquid helium and argue that surface excitations similar to surfons have been previously obtained by numerical calculations and called resonance interface states.

Scientific Council of the Landau Institute, Friday, January 18, 2019, Landau Institute, 11:30 am

P.D. Grigoriev

Linear magnetoresistance in the charge density wave state of quasi-two-dimensional rare-earth tritellurides

The magnetoresistance of a TbTe3 two-dimensional conductor with a charge-density wave (CDW) has been measured in a wide temperature range and in magnetic fields of up to 17 T. At temperatures well below the Peierls transition temperature and in high magnetic fields, the magnetoresistance exhibits a linear dependence on the magnetic field caused by the scattering of normal charge carriers by “hot” spots of the Fermi surface. In the sliding CDW regime in low magnetic fields, a qualitative change in the magnetoresistance has been observed associated with the strong scattering of carriers by the sliding CDW.
[1] A.V. Frolov, A.P. Orlov, P.D. Grigoriev, V.N. Zverev, A.A. Sinchenko, P. Monceau, Magnetoresistance of a Two-Dimensional TbTe3 Conductor in the Sliding Charge-Density Wave Regime, JETP Lett., 107(8), 488-492 (2018)

Department of quantum mesoscopics: seminar, Friday, January 18, 2019, ITF, 3:00 pm

N.E. Nefedkin, A.A. Zyablovskii, E.S. Andrianov, A.A. Pukhov, A.P. Vinogradov (VNII Avtomatiki im. N.L. Dukhova)

Kooperatsiya mod v dvumernykh plazmonnykh lazerakh s raspredelennoi obratnoi svyaz'yu

Issledovana dinamika plazmonnogo lazera s raspredelennoi obratnoi svyaz'yu (DFB lazera) na osnove dvumernoi perforirovannoi metallicheskoi plenki. Dlya takoi struktury mozhno vydelit' dva kharakternykh tipa mod. K pervomu iz nikh otnosyatsya mody, chastota kotorykh nakhoditsya v razreshennoi zone, imeyushchie bol'shie izluchatel'nye poteri i vysokii porog generatsii (svetlye mody). Ko vtoromu tipu otnosyatsya mody, chastota kotorykh nakhoditsya na krayu razreshennoi zony, imeyushchie nizkie izluchatel'nye poteri i nizkii porog generatsii (temnye mody). Pokazano, chto kogda pyatno nakachki men'she razmera poverkhnosti DFB lazera, nelineinoe vzaimodeistvie mezhdu modami periodicheskoi plazmonnoi struktury cherez aktivnuyu sredu privodit k novomu effektu, a imenno k kooperatsii mod [1]. Kooperatsiya mod proyavlyaetsya kak generatsiya svetlykh mod s vysokimi poteryami vmesto generatsii temnykh mod s nizkimi poteryami. Pokazano, chto etot effekt imeet mesto v dvumernykh DFB lazerakh i ne proyavlyaetsya v odnomernykh DFB lazerakh. Vzaimodeistvie svetlykh mod voznikaet iz-za neortogonal'nosti lazernykh mod v oblasti nakachki, gde svetlye mody stanovyatsya sinkhronizirovannymi po faze. Kak sledstvie, voznikaet ikh konstruktivnaya interferentsiya. Prodemonstrirovano, chto vsledstvie kooperatsii mod imeet mesto ushirenie diagrammy napravlennosti vyshe poroga generatsii, chto nablyudalos' v nedavnikh eksperimentakh [2].

[1] N.E. Nefedkin, A.A. Zyablovsky, E.S. Andrianov, A.A. Pukhov, and A. P. Vinogradov, ACS Photonics 2018 5(8): p. 3031-3039.
[2] Tenner, V.T., M.J.A. de Dood, and M.P. van Exter, Measurement of the phase and intensity profile of surface plasmon laser emission. ACS Photonics, 2016. 3: p. 942−946.

Visiting address:

Laboratory building, room 122
Moscow Institute of Physics and Technology
Dolgoprudny, Russia

contact e-mail address: nanotheory@phystech.edu (head M.V.Feigel'man, deputy head I.V.Zagorodnev)

Research topics
  • Mesoscopic electronic systems
  • Superconducting hybrid structures
  • Quantum phase transitions
  • Spintronics
  • 2DEG and quantum Hall effect
  • Quantum magnetism and topological order
  • Physics of quantum computation