Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.issp.ac.ru/lek/gantmakher/art089RE.pdf Дата изменения: Tue Apr 4 11:12:58 2006 Дата индексирования: Tue Oct 2 07:18:10 2012 Кодировка:

Rrydnbdftonr

rE[
(194) 1085-1086 B Physica 194-196 North-Holland

AI{D INSUU\TING PHASES IN THE METASTABLE INTERPLAY OF ST'PERCONDUCTING

HIGtI-REsIsTAlfcE STATESOF fiIE G"so SBO ALLOY
V.F.Ganturakher, V.M.Teplinskii, Institute of Solid State Physics, V.N.Zverev, and O. I.Barkalov 142432 Chernogolovka, Russia

Ag

EISEVIER

ffi


r Physica 194-196 1994t1085-10U6 B North-Holland

pltY$t[A
V.N.Zverev, and 0. I.Barkalov t42432 Chernogolovka, Russia

AND INSULATING PHASES IN TTIE METASTABLE INTERPLAY OF SUPERCONDUCTING STATES oF THE G"SOSBO ALLOY HIGH-RESISTANCE V.F.Gantmakher, V.M.Teplinskii, Institute of SoIid

State Physics,

Temperature dependences of the resistance R(T) of the alloy GaSb at diffefrom the high-pressure metastable metallic rent stages of its transformation (I-) phase are measured. Absolute values of (M-) phase into the an insulating R at these stages span more than eight orders of magnitude. The superconducttakes place in the low-resistance states aI T = 4.6K. It ing (S-) transition to an insulating i.e. gives way to a steep increase of the resistance, states. in the high-resistance transition at the Same temperature In three dimensions (3D), the quasineentrant superconducting ( qrS- ) transition usually takes place near threshold [1]. Recthe localization ently, some experimental indications can be appeared that qrS-t-ransition realized not only in granular material but in the homogeneously disordas weII I2l or, at ered material Ieast, in materials which cannot be treated as random mixture of conducIn this connectors and insulators. tion, we compared in this paper the R(T) dependence above the onset of with that at low the qrS-transition temperatures where R increases with reducing T. Our material, the alloy G"SOSBO , which under is one of those alloys the high pressure can be obtained in a metastable M-phase and then transformed into I-phase by heating I3l. one can get a Dosing the heating, row of intermediate states and measure the dependence R(T) in them at The alloy Ga-Sb low temperatures. transforms in accordance apparently scheme: the l-phase with the fractal thinstructure appears as a fractal current the ning and entangling the paths t4l. fndeed, even after initial resistance of the sample has been increased by 8 (! ) orders of value magnitude (estimated starting . cm) we being 100 of resistivity did not reach the stat,e which could judging be regarded as an I-state to T=O of from formal extrapolation the conductance (T). The first four orders of magnitude in changing R are not accompaniSof the any changes ed by transition. This confirms that only a part of the sample is yet involved The physicinto the transformation. of those domains where aI properties preserved remain the S-transition volume reduces unchanged but their topology becomes rapidly and their more complicate. Further increase of in R leads to appearance of tails and then curves first the transition the to the qrS-transition lL,2l: to become zero and resistance fails starts to increase with lowering the temperature. Fig.1 exposes the experimental by are labelled data. The states number q

q : Iog (RAi'
where R.
IN

h=ef
the

,
of It the can

is

resistance state.

sample in

the initial

@ 1994 ElscvicrScience B.V. All rishts reserved 0921-4526191/$07.00 -1526Q3)Err23-4 1 ssD/ 092


1086

t, T- r.o ! I

" o,5

1

2

3 T1/2. K1/2

4

5

0.1 oo(o),lorrm-tcm-t Fig.2 the systreating approach instead, such as a whole and involving tem as spin density waves' paired ideas [5], or supposing electron crystals of the order paramagnitude finite of the CooPer meter and existence of the S-I tranpairs at the I-side sition [6]. A similar Phenomenon - a crossover dependbetween S- and I-transitions the expeniing on the conditions of ment has been seen in quasi-lD condis uctor TaSe^ l7i. The similaritY
J

Fig.1 be seen from the curve q:7-8 that in states there is the high-resistance a trano natural S-resPonse at all: does exist at the temperatunsition c c re T but the resistance at T ( Tincreases instead of decreasing. that' at from Fig.1 follows It q large enough the T > T and with c changes in the conductance are prop-

ortional

to T"

1/? "

. The straight

line

do(T) = do (01 , ^rL/z
describes T the the data above Tc. d(T)-6^ U(T) Below may

difference C at

the that emphasized bY the fact of the conducting domains d,imensions maY turn to structure on a fractal low. be rather REFERENCES 1. 2. 3. 4. 5. 6. 7. aI , M.Kunchur, Y. Z.Zhang, et 4062 (1'987) Phys.Rev. B 36, et aI' V.Gantmakher, V.Teplinskii (L992) JETP Letters 56, 309 E.G.Ponyatovsky and O. I.Barkalov' Mater.Sci.ReP. 8, 147 (f992) V.Gantmakher, S.EsiPov et ?1, Sov.Phys.-JETP 70, 373 (1990) R.Moulopoulos and N.ll.Ashcroft' Phys.Rev.Lett. 69, 2555 (t992) M.Paalanen, A.Hebard and R'Rue1, 69, 1'604 (1'992) Phys. Rev. Lett. Y.Tajuma and K.Yamada, J.Phys'Soc' Jpn. 69, 495, 3307 (1'984)

change the sign

some temperature as a Parameter T" and T* vs domains in

Tx. Let us take oo(o) of
U

the state

and PIot

d^(O).Than we get the (dO,T)

three

Plane which can be named M-, S- and l-domains - see Fig-Zof exPlanation The most natural would suppothe observed phenomenon se that current Paths cross a kind with nonof a S-I-S-. . . -structure tunnelJosephson but quasiparticle It through l-domainsing cuments is not clear yet whether such approMaYbe we need quantum ach is valid.