Pressure controlled transition into a self-induced topological superconducting surface state

Abstract

Ab-initio calculations show a pressure induced trivial-nontrivial-trivial topological phase transition in the normal state of 1T-TiSe2. The pressure range in which the nontrivial phase emerges overlaps with that of the superconducting ground state. Thus, topological superconductivity can be induced in protected surface states by the proximity effect of superconducting bulk states. This kind of self-induced topological surface superconductivity is promising for a realization of Majorana fermions due to the absence of lattice and chemical potential mismatches. For appropriate electron doping, the formation of the topological superconducting surface state in 1T-TiSe2 becomes accessible to experiments as it can be controlled by pressure.

Controlling the semiconductor–metal transition in Cu-intercalated TiSe2 by applying stress

“…[1][2][3][4] One of the most common and functional materials among them is titanium diselenide (TiSe 2 ). It demonstrates a charge density wave (CDW) transition below 200 K, 5,6 the emergence of superconductivity either upon an appropriate intercalation with copper 6 or under the action of an applied high pressure, 7 a topological transition under high pessure, 8 a gyrotropic electronic order, 9 and other phenomena. TiSe 2 also finds applications in optoelectronics, 10,11 electrochemical devices, 10 photonic devices, 12 mode-locked ultrafast lasers, 13 heterojunctions, 14,15 and in other appliances.…”

Molecular beam epitaxy growth and scanning tunneling microscopy study ofTiSe2ultrathin films

“…Upon intercalation with copper 15 or applying pressure, 16 the CDW ordering melts and superconductivity develops with a critical transition temperature of several Kelvin, indicating com-petition between CDW and superconductivity in TiSe 2 . Recently, self-induced topologically nontrivial and chiral superconducting phases have been predicted in pressurized TiSe 2 17 and TiSe 2 monolayer, 18 respectively, which might harbor the long-pursuing Majorana fermions. 19 According to Raman spectroscopy study, T CDW can be enhanced as the thickness of mechanically exfoliated TiSe 2 films is reduced to nanometer scale.…”

“…24), originate predominantly from Ti 3d bands. [10][11][12]17 A minor change (< 50 meV) in peak energy positions might be caused by the dimensionality and/or electron-doping effects from the underlying n-doped graphene/SiC(0001) substrate. Remarkably, the Se 4p band-derived occupied electron DOS are considerably pushed to lower energies as the film thickness reduces, in particular in TiSe 2 monolayer, primarily due to the quantum confinement effects.…”

Особенности гальваномагнитных явлений в сильных магнитных полях в бикристаллах кручения 3D топологического изолятора Bi-=SUB=-1-x-=/SUB=-Sb-=SUB=-x-=/SUB=- (0.07&le; x&le; 0.2)

“…Однако в этих бикри-сталлах выявлены особые квантовые осцилляции галь-ваномагнитных эффектов, связанные с составляющими слоями интерфейса, характеризующими более высокую плотность состояний и значительно более тяжелые носители заряда, чем в кристаллитах. Судя по этим данным, бикристаллы 3D ТИ Bi 1−x Sb x (0.07 < x < 0.15) могут быть полезны для изучения ряда важных проблем современной физики, в том числе проблем сверхпрово-дящих систем с узловыми точками Дирака и Маджорана (Majorana) моды [18][19][20][21], а также вопросов связанных с квантовой спин Холл фазой [6] и др.…”