Density of States in Multilayer Sandwiches

Abstract

The density of states of finite metal-semimetal systems is considered in the case of boundary conditions that assure the damping of electronic states a t infinity. The density of states of the transition region metal-semimetal is investigated which is found to be strongly dependent on the shape of the transition layer. Special a.ttention is paid to the case when in one part of the system, in the metal, the coherence of the motion of the electron is broken, while in the other part, in the semimetal, the electron moves coherently. Under this condition, the oscillations of the density of states of systems consisting of a metallic film covered on both sides with the semimetal, and systems consisting of two metallic films with a semimetallic interlayer are considered. Within the model described, one can understand the experimentally observed behaviour of To (the temperature of the superconducting transition) a t small thicknesses of the semimetallic layer. PaCCMaTpHBaeTCH IIJIOTHOCTL COCTOFIHHH KOHeWIbIX CHCTeM MeTaJlJl-nOJIyMeTaJIJI npH rPaHHsHbIX yCJIOBkl%IX, 06eCIIesklBaIOIqHX 3aTyXaHkle 3JIeKTPOHHbIX COCTOHHHH Ha 6ec~o-He9HOCTII. MCCJIe,IIyeTCH IIJlOTHOCTb COCTOHHHfi IIepeXOAHOH 06JIaCTPi MeTaJU-IIOJIy-BHklMaHHe YHeJleHO paCCMOTpeHklI0 CnysaH, KOrHa B OEHOH gaCTH CHCTeMbI, B MeTaJIJIe, 3JIeKTPOH , QBkllKeTCH KOrepeHTHO. npkl 3TOM YCJIOBPiX paCCMOTpeHb1 OC4klJIJIHlJHH IIJIOT-MeTann, KoTopaH o~a3anacb cHmbHo 3 a~~c~w e f i OT i#opMbi nepexonHoro CJIOR. Oco6oe KorepeHTHocTb ABklmeHm a n e~~p o~a HapymeHa, a B HpyroH qacTH, B noayMeTame, HOCTH COCTORHHH cncTeM, COCTORI~LIX ~3 MeTammsecKoH nneHm, noKpbmoH c o 6 e~x CTOPOH nonyMeTamnoM, H cmTeM, COCTORWE~X 143 ~B Y X MeTanamsecmx nneHoK c nony-MeTannmsecKoH npocnoHKoH. B onmaimoH MoAem MoxeT LIT^ IIOHHTO ~aGnmnae~oe Ha s~c n e p~~e~~e noseneme T, (TeMnepaTypbI cBepxnpoBomuero nepexona) n p~ MamIx Tomumax nonyMeTanmisecHoro CJIOR. l) Moscow 123 182, USSR.