dHvA EFFECT IN THE NORMAL STATE OF THE HIGH TcA-15 SUPERCONDUCTORS Nb3Sn AND V3Si

HAL Id: jpa-00217600

https://hal.archives-ouvertes.fr/jpa-00217600

Submitted on 1 Jan 1978

HAL is a multi-disciplinary open access

archive for the deposit and dissemination of

sci-entific research documents, whether they are

pub-lished or not. The documents may come from

teaching and research institutions in France or

abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est

destinée au dépôt et à la diffusion de documents

scientifiques de niveau recherche, publiés ou non,

émanant des établissements d’enseignement et de

recherche français ou étrangers, des laboratoires

publics ou privés.

dHvA EFFECT IN THE NORMAL STATE OF THE

HIGH TcA-15 SUPERCONDUCTORS Nb3Sn AND

V3Si

A. Arko, D. Lowndes, F. Muller, L. Roeland, J. Wolfrat, F. Mueller, G. Webb

To cite this version:

JOURNAL DE PHYSIQUE

Colloque C6, supplément au n° 8, Tome 39, août 1978, page C6-412

dHvA EFFECT IN THE NORMAL STATE OF THE HIGH T

A~15 SUPERCONDUCTORS Nb

Sn AND V

S i *

A.J.Arko,+ D.H.Lowndes,+'++ F.A.Muller,** L.W.Roeland,** J.Wolfrat,** F.M.Mueller1"*" and G.W.Webb++.

Materials Science Division,Argonne National Laboratory, Argonne, IL60439 USA. +

Department of Physics, University of Oregon, Eugene,OR 97403 USA.

tt

Physics Laboratory, University of Nijmegen,Nijmegen,The Netherlands.

Natuurkunding Laboratorium, University of Amsterdam, Amsterdam, The Netherlands Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA 92093 USA.

Résumé.-Des oscillations dHvA ont été observées pour Nb.Sn, dans le plan (110) et pour V,Si, dans deux orientations, en utilisant des monocristaux de haut rapport de résistance et des champs magné-tiques allant jusqu'à 400 kOe. Les fréquences dHvA obtenues pour Nb_Sn peuvent être interprétées comme une série d'ellipsoides concentriques centrées en M.

Abstract.- dHvA oscillations have been observed in Nb,Sn in the (110) plane and in V,Si at two orien-tations using single crystals of high resistance ratio and magnetic fields up to 400 kOe.The dHvA frequency data for Nb~Sn can be interpred as a series of nested ellipsoides centred at M.

The current high level of interest in A-15 materials is due to the recent and continuing dis-converies of the coexistence of a variety of ano-malous normal state properties at both high and low temperatures, with the highest T materials showing the most puzzling behaviour. A variety of physical models ascribing special features to either the phonon or electron distributions have been invoked to explain the normal state properties. Our dHVA results are a first step in providing a microscopic test of the various electronic models for high T material. The only prior dHvA measurements on an A-15 being the recent results of Arko et al /l/ for Nb,Sb (T ^ 0.2 K ) . Magneto-thermal oscillations were previously observed 111 in V.Ge (T ^ 6 K ) .

The Nb,Sn crystals were grown over a period of four months by closed tube vapor transport with iodine as the transporting agent. An inductive mea-surements of the actual dHvA crystal showed a T of 17.8 K and a width(10%-90%) of 0.07 K. Resisti-vity measurements confirm that the samples undergo a martensitic transformation at 51 K. Assuming an approximate extrapolation function /3/ we estimate R(300 K)/R(0 K) = 50 and R(0 K)= 1.5 pficm / 4 / . From this residual resistivity we estimate an

elec-Tfork supported by the U.S.Department of Energy, the National Science Foundation(USA), the Stit-ching voor Fundamenteel Onderzoek der Materie (The Netherlands), and NASA (USA).

o

tron mean free path of about 500 A and w T £ 1 in magnetic fields above 230 kOe, where OJ is the cy-clotron frequency and T is a mean scattering time. This consideration is suggestive of the scattering time being hig enough to see the dHvA effect.

The V. specimen was grown by float zoning. No resistance ratio or T measurements were made on

c it.

Nb3Sn

75° FROM [lOO]

i ^PICKUP COIL SIGNAL

H ~~ 4 0 T . \ Hc2 TRANSITION

^ ^ - • • V ^ ^ ^ FIELD STRENGTH K I

d H v A - ^ ^ ^ ^ - v . ^ / I

OSCILLATIONS—::*—^—— f I ^ ^

F i g . 1 : Dual t r a c e s of a t y p i c a l high speed chart recording for Nb,Sn, showning the decay of a 40 T magnetic f i e l d p u l s e and t h e simultaneous r e c o r -ding of dHvA o s c i l l a t i o n s followed by the super-conding t r a n s i t i o n a t H . versustime.The apparent o s c i l l a t i o n s below H „ a r e noise generated in the pickup c o i l due to eddy c u r r e n t s , f l u x jumps, etc. and not p e r i o d i c in 1/H.

The experiments were conducted at the Univer- sity of Amsterdam's 400 kOe "slow pulsed field" fa- cility using the magnet in the free inductive decay mode to minimize noise 151. The output of a compen- sated dHvA pickup coil was differentieted twice,fil- tered to take out some of the dc voltage resulting from incomplete coil compensation, amplified, and displayed directly on the recorder. A typical recor- der tracing is shown in figure 1.

O 10 20 30 40 50 60 70 80

[0011 11111 [1101

MAGNETIC

FIELD

Fig. 2 : dHvA frequencies for Nb3Sn in the (110) plane. The solid circles (and typical error bars) are the experimental results.Accuracy of orienta- tion in the (110) plane is l". The frequencies at a given orientation are reproducible to within a few %. The solid lines are generated from the Fermi surface model and band structure calculation of reference 181.

The dHvA oscillations were analyzed by marking the positions of successive oscillation peaks and making a plot of oscillation number vensus 1/H ; the slope of this "number plot" gives the dHvA frequen- cy directly and was generally found to be a good straight line. Beat structure, while obviously pre- sent at some orientations, was difficult to resolve because of the few oscillations. Nevertheless, it is possible to resolve several branches in the Nb3Sn data. Figure 2 displays the dHvA'frequencies (open circles) fournd for Nb3Sn in the (110) plane, while the limited data for V Si are given in table I. The

3

typical error estimates indicated in figure 2 are conservative, based on a maximum possible counting error of one-half oscillation.

TABLE I

dHvA Frequencies for V3Si

Orientation Fr uency 84

(10 gauss)

12

4.60

D

To interpret our Nb Sn results we have used

3

the results of a new band calculation /6/ which has its roots in the work of Mattheis /7/. The solid li- nes in figure 2 are the predicted theoretical fre- quencies 161. The correspondence between the obser- ved frequencies and those labeled a , 6 , and y is good. Based on this we conclude that the observed frequencies are consistent with a set of nested ellipsoids at M, similar to the observations in Nb3Sb / I / and V3Ge /2,7/.

We acknowledge the help prov-ided by Dr.Sven Hornfeldt in connection with the sample rotator de- sign, and by Mr.Weiznebeck in connection with data logging.

References

/I/ Arko,A.J., Fisk,Z. and Mueller,F.M.,Phys.Rev. B16 (1977) 1387.

-

/2/ Graebner,J.E. and Kunzler,J.E.,J.Low Temp.Phys.

1 (1969) 443.

-

/3/ Webb,G.W.,Fisk,Z.,Engelhardt,J.J.and Bader,S.D. Phys. Rev.

B15

141 Woodard,D.W. and Cody,G.D. ,Phys.Rev. g(1964) A1 66.

/5/ Gersdorf,R;,~uller,F.A. and Roeland,L.W.Rev. Sci.Instrum.

36

161 Van Kessel,A.T., Myron,H.W. and Mueller,F.M., to to be published.