The Meissner effect in TaSe3

The Meissner effect in TaSe3

Physica B 165&166 (1990) 887-888 North-Holland THE MEISSNER EFFECT IN TaSe3 Shoichi NAGATA, Shuji EBISU, Tsuyoshi AOCHI, Yasuhiro KINOSHITA and Susum...

380KB Sizes 12 Downloads 160 Views

Physica B 165&166 (1990) 887-888 North-Holland

THE MEISSNER EFFECT IN TaSe3 Shoichi NAGATA, Shuji EBISU, Tsuyoshi AOCHI, Yasuhiro KINOSHITA and Susumu CHIKAZAWA Department of Applied Materials Science, Muroran Institute of Technology, 27-1 Mizumoto-Cho, Muroran 050. Japan The Meissner effect of TaSe3 is studied using a SQUID magnetometer. Susceptibility X does not show any significant variation of diamagnetism, with magnetic field parallel and perpendicular to crystalline b-axis over a low field range of 7.2 mOe to 4.0 Oe. The diamagnetic X is much less than -3.0x 10-3 emu /'cm 3 . Superconducting thin filaments are individually isolated above 0.40 K. 1. INTRODUCTION

Resistivity drop of TaSe3 below 2.1 K could be associated with superconductivity. A French group[l] reported no chan§e in the magnetic susceptibility to one part in 10 of total flux exclusion from the sample at temperatures as low as 1.2 K and fields as low as 1.0 Oe. On the other hand, Cornell University group [2] observed diamagnetic susceptibility X and put an interpretation of a superconducting coupling throughout larger volume at lower temperatures. Experimental evidence has been ambiguous and the results of magnetic measurement are less conclusive. We present a systematic study of the superconductivity of TaSe3.The diamagnetic susceptibility measurements are carried out to establish the presence or absence of diamagnetism. Typical sample size of the investigated sample was 10 JLmX5.0 JLmx6.0 mm(needle-like whisker) and the residual resistance ratio was p (300 K) /' p (4.2 K) = 100. The diamagnetic X was measured with an rfSQUID magnetometer using 3He cryostat. The sensitivity is sufficient to detect changes of 2 X10- 9 emu in the magnetic moment for a field of 7.2 mOe. The measurements of X with field applied parallel and perpendicular to crystalline b-axis were done. Background correction and the filling fraction correction have been precisely made in each measurement.

0.6

...... ~ 0.4-

0.2 0.00

2

3

4-

T [ K ) Fig. 1 Temperature dependence of resistivity for different current densities. 0921-4526/90/$03.50

u

~ E -0.02

~

......... -.............. -..

0 3

In (2.0mgl

. 0

-5.0 x1lj'8 3

H=7.2mOe

..

~

:r: -0.04 '\ :::;:

X"

-1.0X1C]7 3

E-

-0.06

-1. 5X1 c)7

-0.08 3.30

3.40

T(KI

3.50

Fig. 2 Susceptibility change of Indium used as the standard signal. The ordinate of the right side represents a moment change of In ( 2.0 mg) at the transition in a field of 7.2 mOe. 2. RESULTS AND DISCUSSION 2.1. Normal-state In the temperature range of 4.2 K < T < 50 K. the normal state electrical resistivity along b-axis is well represented by. n p(T) Pot AT (I) n = 2.8 ± 0.1. Q

'cm(Knj -1 •

where p Dis the temperature-independent residual resistivity. The power law expression of eq. (1) indicates a characteristic of the quasi-one-dimensional conductor [3].

52 NO.8 ~

0

E

A = (2.0 ± 0.4) x 10- 9

1.0

a:

Standard Signal C'1

© 1990 -

2.2. Current dependence of the resistivity The temperature dependence of the resistivity between 1.0 and 4.2 K is measured. Figure 1 shows experimental results for several different currents densities. The resistivity depends strongly on the current density. The sharp drop in p is could be associated with.the superconducting transition. The superconductivity is almost destroyed if the current density exceeds a value of 3.0 A/'mm 2 in the temperature region above 1.0 K.

Elsevier Science Publishers B.V. (North-Holland)

S. Nagata, S. Ebisu, T. Aochi, Y. Kinoshita, S. Chikazawa

888

6.0 r----,---,---,---,---,.-----,

::J

a

E

OJ cD

-1 o -2

E

TaSe3 (0.57 mgl HII = 7. 2 mOe

I

()

"":::J E

OJ

~

E

1. 9

2.0

2.2

2.1

Fig. 3 Temperature dependence of magnetic moment of 0.570 mg TaSe3 in 7.2 mOe parallel to b-axis around 2.1 K. No anomaly occurs at 2.1 K. 2.3. Diamagnetic susceptibility Dc susceptibility X refers to an integrated temperature change of magnetization Mdivided by a constant applied field H. (X; M/H ). The magnetization change at the superconducting transition of a needle shaped piece of Indium ( ~ 2.0 mg ) is used for the calibration of its value. A representative datum for 7.2 mOe is shown in Fig. 2. The sample mass of TaSe3 was about 0.60 mg for each dc-susceptibility measurement. in which pieces of whisker crystals were separated with GE-varnish to prevent these whiskers from the interpenetration and the contact problem because the compacted randomly oriented massive sample would exhibit totally different behavior from our present data. The susceptibility X does not give any indication of an abrupt change at 2.1 K for sensitivity as high as 1. 5 x 10-g emu in the change of the magnetic moment. which is shown in Fig. 3. Figures 4 and 5 show the temperature dependence of the susceptibili(")

E

()

E

OJ

N

1.0 0.0

I

a

><

-1.0 0.0

_- ..

- ...

~-.

1.0



...

.....

.---.

7,2 mDe

2.0

T1K)

3.0

3.0



(")

E

()

"":::J E

OJ

1.0

(")

I

a

><'"

...

2.0

0.0

.......... ~:.&

••••

• •

0

0.3 0.41.0 2.0

De De De De

••

-1.0 0.0

1.0

2.0

TlKl

I

a

~

T(Kl

"":::J

.. 0.5 De

(")

3.0

Fig. 4 Temperature dependence of the parallel susceptibility( H II b ) for several fields. The sample weight is 0.570 mg ( 7.05 x 10- 5 cm 3. 6 mm length. 100 whiskers l for measurements.

4-.0 2.0



--:0•••_......

~o. . .

.. 1.0 De [!J 2.0 De .. 4-. ODe

• .......' ••••.......,t't.

~~ ::~., o. a1---:.a.;~~~,~ ;'Oo;-.. ::-..-=-o-=-o-=-.-=-o-:i ..~..~-...., o· -2.0

---1.--;'.1-;.0;---'----;:;2.1-;.0;---'-----n"3. 0

O·L.;::-O

T(Kl Fig. 5 Temperature dependence of the perpendicular susceptibili ty ( HJ.. b ) for several fields. The sample weight is 0.642 mg ( 7.94 x 10- 5 cm 3. 3 mm length. 292 whiskers lfor measurements. Diamagnetic correction was not made. ty of TaSe3 for several applied fields parallel and perpendicular to crystalline b-axis. Data at 2.8 K are taken to be zero in X. Scattering of the data could be attributed to magnification from the extremely small signal to the value normalized by unit volume. in particular low fields. Our results represent the inherent characteristic of a single whiske~ The susceptibility X does not show any systematic change at lower temperatures as low as 0.40 K in the field as low as 7.2 mOe. The difference between zerofield cooled and field-cooled susceptibility in 0.40 De is negligible small and does not make sense. The superconducting thin filaments in the whisker would have an effective radius much smaller than the penetration depth ;t. Then. this penetration reduces the value of X [4]. Progressive increase of the diamagnetic X below 2.1 K is not observed even in low field of 7.2m De. therefore. these filaments are individually isolated fairly well avobe 0.40 K. Further investigation of TaSe3 is now in progress and the result will be reported elsewhere. ACKNOWLEDGEMENTS The authors thank Dr. K. Yamaya for providing us with the samples. The present work was supported by a Grant-in-Aid for Scientific Research from Ministry of Education. Science and Culture. REFERENCES [1] P. Haen. F. Lapierre. P. Monceau. M. NunezRegueiro and J. Richard. Solid State Commun. 26 (1978) 725. [2] R. A. Buhrman. C. M. Bastuscheck. J. C. Scott and J. D. Kulick. Superconducting diamagnetism of TaSe3 and NbSe3' in AlP Conference Proceeding No. 58. eds. D. U. Gubser. T. L. Francavilla. J. R. Leibowitz and S. A. Wolf ( American Institute of Physics 1980 l pp. 207-215. [3] S. Nagata. H. Kutsuzawa. S. Ebisu. H. Yamamura and S.Taniguchi. J. Phys. Chem. Solids 50 (1989) 703. [4] S. Nagata. Y. Kinoshita. S. Ebisu and S. Chikazawa. Why is the Meissner effect suppressed strongly in TaSe3 1. this volume.