# Theoretical seminars in Kapitza Institute for Physical Problems

## Large deviations of surface height in the Kardar-Parisi-Zhang equation

31 May in 11:30

Baruch Meerson (Hebrew University of Jerusalem)

The Kardar-Parisi-Zhang (KPZ) equation describes an important universality class of nonequilibrium stochastic growth. There has been a surge of recent interest in the one-point probability distribution P(H,t) of height H of the evolving interface at time t in one dimension. I will show how one can use the optimal fluctuation method (OFM) to evaluate P(H,t) for different initial conditions and in different dimensions. In one dimension the central part of the short-time height distribution is Gaussian, but the tails are non-Gaussian and strongly asymmetric. One interesting initial condition is an ensemble of Brownian interfaces, where we found a singularity of the large deviation function of the height at a critical value of |H|. This singularity results from a breakdown of mirror symmetry of the optimal path of the system, and it has the character of a second-order phase transition. At d>2 the OFM is valid, in the weak-coupling regime, at all times. Here the long-time height distribution P(H) is time-independent, and we use the OFM to determine the Gaussian body and strongly asymmetric non-Gaussian tails of P(H).

## Elektronnye svoistva dopirovannykh khal’kogenidov vismuta

7 June in 11:30

A.Yu. Kuntsevich (FIAN)

Khal’kogenidy vismuta yavlyayutsya topologicheskimi izolyatorami s naibol’shimi shirinami zapreshchennoi zony. Pri dopirovanii Bi_{2}Se_{3} med’yu, strontsiem ili niobiem Bi_{2}Se_{3} stanovitsya sverkhprovodyashchim (predpolozhitel’no, nematicheskim topologicheskim sverkhprovodnikom).
V doklade budet dan obzor imeyushchikhsya na segodnyashnii den’ dannykh o nematicheskoi sverkhprovodimosti dannogo materiala, v tom chisle i nashi rezul’taty o korrelyatsii nematichnosti so strukturnymi iskazheniyami [arXiv:1801.09287].
Takzhe ya rasskazhu o chasto obsuzhdaemom v literature izmerenii fazy Berri iz magnitoostsillyatsii. Nami privedeny prostye makroskopicheskie argumenty [Phys. Rev. B 97, 195431 (2018)], pochemu v real’nykh topologicheskikh izolyatorakh eta faza mozhet sil’no otlichat’sya ot teoreticheski ozhidaemogo znacheniya.

Seminars are held on Thursdays in the conference hall Kapitza Institute for Physical Problems in Moscow, beginning at 11:30.

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