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Flux flow resistivity in single crystal YBa2Cu3O7−δ
Physica B 163 (1990) North-Holland
242-244
FLUX FLOW RESISTIVITY W.K. KWOK, Materials
U. WELP.
Science
Division.
IN SINGLE CRYSTAL
G.W. CRABTREE,
Argonne
National
K.G.
Laboratory,
YBa,Cu,O,_, VANDERVOORT’ Argonne,
and J.Z.
LIU
IL 60439. USA
AC magnetoresistance measurements were performed on twinned single crystals of YBa,Cu,O,_, to study the effect of dissipative flux flow motion due to Lorentz force. We report the first direct observation of Lorentz force induced flux flow resistivity in high-T, superconductors which varies as sin’(e) with respect to transport current-magnetic field orientation. However, the intrinsic broadening of the resistive transition in magnetic field exists even in the absence of Lorentz force and hence cannot be explained by flux flow dissipative resistivity.
1. Introduction The anomalous broadening of the resistive transition in finite magnetic field in the high-T, superconductors is an important unresolved question. This behavior has been attributed to flux motion [ 1,2], field dependence of the critical current in Josephson junctions [3] (perhaps in the twinning planes) and fluctuation conductivity [4]. Thermally activated flux creep models [5] have been used to qualitatively explain the appearance of resistance in a field from dissipation of energy due to movement of vortices. In order to investigate whether the dissipative flux flow resistance is due to the transport current induced Lorentz force, a simple test can be applied to magnetoresistive measurements involving transport current(l)-magnetic field (H) geometries where H I( I gives zero Lorentz force and H I I induces maximum Lorentz force. So far, experiments [6] conducted on the high-T, superconducting films and single crystals with such currentfield geometries have yielded no apparent differences. Therefore, the explanation for the resistive broadening in magnetic fields based on flux flow phenomena is suspect. To address these issues quantitatively, we recently [7] measured ac magnetoresistivity on a high quality single crystal of YBa,Cu,O,_, in various current-field geometries to study the effect of Lorentz force on vortex motion. We found for the first time that the shape of the superconducting resistive transition curve in field for our YBa,Cu,O,_, single crystals is dependent on the current-field geometry. In this paper we follow up on our earlier measurements and include results on the angular dependence of the
magnetoresistance with respect to current-field etry which show the effect of Lorentz force flux flow resistivity in YBa,Cu,O, fi
geominduced
2. Experiment Single crystals of YBa,Cu,O,_, were prepared by a partial melting method described elsewhere [8]. Many crystals are produced in a single batch processing and exhibit sharp transitions with T, > 90 K. These crystals are platelets in shape with average dimensions of 0.05 X 2 X 3 mm’. AC resistivity was measured on two of these crystals by the standard four wire method with a measuring current of 0.1 mA at 17 Hz in fields up to 8 T. Current and voltage electrical leads were attached onto the a-b plane of the crystal with silver paint. Magnetic fields up to 8T were applied in the a-b plane of a single crystal at either parallel, perpendicular, or 30” off parallel geometry from the transport current direction. The parallel geometry leads to zero Lorentz force on the vortices by the transport current whereas the perpendicular geometry leads to maximum Lorentz force acting on the vortices. In addition, the 30” current-field angle geometry yields an intermediate Lorentz force value. In a second single the angular crystal of YBa,Cu,O,_, , we measured dependence of the flux flow resistivity by varying the angle between the transport current and the magnetic field in fixed field and temperature in the supeconductive resistive transition region.
3. Results and discussion
’ Also at University Partially Argonne
of Illinois at Chicago, Chicago, supported by Division of Educational National Laboratory.
OY21-4526/90/$03.50 (North-Holland)
0
Elsevier
Science
Publishers
IL 60680. Programs,
B.V.
Figure for three
la shows the resistivity current-field geometries
versus temperature in a magnetic field
243
W. K. Kwok et al. I F[ux flow resistivity in single crystal YBa,Cu,O,_,
Q 50 Experimental Data 0
89.0
91 .o
90.0
’ ’ ’s’ ’ -50 0
0.5
92.0
T(K) 200
. , . - I
. , - I . - .
sin’(e)
’
’ 50
3’ ’ ’ 1’ ’ 3’ ’ ’ ’ ’ ’ 3’ ’ ’ 100
150
200
250
angle
I 8 . . . ’
Fig. 2. Resistance versus current-field orientation angle at T = 91.22 K and H = 1.5 T. The solid line shows a fit to sin% behavior.
Fig. 1. (a) Resistivity versus temperature at 8 T for III H, I I H, and I at 30” from H. (b) Same as above with H = 2 T.
of 8T. The difference between the three curves demonstrates the evolution of flux flow resistivity with respect to current-field geometry. The transverse (H I I) geometry has the highest resistance value whereas the longitudinal (H I] I) geometry shows the lowest resistance values consistent with a flux flow resistivity induced by the Lorentz force on the vortices. A temperature sweep with magnetic field oriented 30” with respect to the transport current yields a resistivity curve lying between the transverse and longitudinal geometry resistivity curves. The zero resistance temperature signalled by an abrupt drop in resistivity at 89.1 K is the same for all three curves and hence independent of the current-field orientation. Figure lb shows the same measurement in a field of 2 T. The flux flow excess resistivity is less pronounced here than in the 8 T curves due to the lower magnetic field but the abrupt drop in resistivity at low temperatures is also evident. Both the 8 and 2T results show that the zero resistance temperature is independent of the current-field orientation within our experimental temperature resolution. Other single twin domain and
untwinned single crystals [9] exhibit a monotonic decrease to zero resistance, but the zero resistance temperature remains independent of the current-field orientation. The differences in the shape of the resistive transition curves among different samples are probably due to sample dependent pinning characteristics. Figure 2 shows the angular dependence of the resistance with respect to the current-field orientation. The data was taken on a second single crystal of in the superconducting resistive transiYBa,Cu,O,_, tion region at a fixed temperature of T = 91.22 K in a constant magnitude of a magnetic field of H = 1.5 T while varying the magnetic field direction with respect to the transport current direction. The result demonstrates that the dissipative resistance follows a sin% periodicity as expected from Lorentz force dissipation
[lOI. Our measurements show that Lorentz force induced flux motion manifests itself as excess resistivity in the superconducting resistive transition in finite magnetic field and follows a sin% dependence with respect to current-field orientation. This excess resistivity due to flux flow only affects the shape of the resistive transition and cannot account for the inherent broadening in the resistive transition in a magnetic field as proposed by Tinkham [l] since the zero resistance temperature in a finite field remains apparently unchanged. Therefore, the anomalous broadening of the resistive transition in a finite field seen even in the absense of a Lorentz force in the high-T, superconductors cannot be explained by a flux flow model and may be an intrinsic property of the material which must be investigated at a more microscopic scale.
244
W. K. Kwok
et al.
I Flux flow resistivity
in single crystal
Acknowledgements This work was supported by the US Department of Energy, Basic Energy Sciences-Materials Science contract #W-31-109-ENG-38 (WKK, GWC, JZL) and the National Science Foundation, Office of Science and Technology Centers under contract #STC-8809854 (VW, KGV), Science and Technology Center for Superconductivity, University of Illinois, UC).
[6]
References [7]
Ill M. Tinkham, Phys. Rev. Lett. 61 (1988) 1658. PI T.T.M. Palstra, B. Batlogg, L.F. Schneemeyer and J.V. Waszczak, Phys. Rev. Lett. 60 (1988) 1662. [31 D. Browne and B. Horowitz, Phys. Rev. Lett. 61 (1988) 1259. M.A. Dubson, S.T. Herbert, J.J. Calabrese, D.C. Harris, B.R. Patton and J.C. Garland, Phys. Rev. Lett. 60 (1988) 1061. [41 B. Oh, K. Char, A.D. Kent, M. Naito, M.R. Beasley, T.H. Geballe, R.H. Hammond, A. Kapitulnik and J.M. Graybeal, Phys. Rev. 37 (1988) 7861. Macroscopic MagPI For a review, see A.P. Malozemoff,
[8] [9] [lo]
YBa,Cu,O,_,
netic Properties of High Temperature Superconductors, in: Physical Properties of High Temperature Superconductors, D. Ginsberg, ed. (World Scientific, Singapore, 1989). K. Kitazawa, S. Kambe, M. Naio, I. Tanaka and H. Kojima (pre-print). H. Iwasaki, N. Kobayashi, M. Kikuchi, S. Nakajima, T. Kajitani, Y. Syono and Y. Muto (pre-print). N. Kobayashi, H. Iwasaki, H. Kawabe, K. Watanabe, H. Yamane, H. Kurosawa, H. Masumoto, T. Hirai and Y. Muto (pre-print). K.C. Woo, K.E. Gray, R.T. Kampwirth, J.H. Kang, S.J. Stein and R. East (pre-print). W.K. Kwok, U. Welp, G.W. Crabtree, K.G. Vandervoort and J.Z. Liu, Proc. Int. Conf. on Materials and Mechanisms of Superconductivity: High-Temperature Superconductors, Stanford, CA, July 23-28, 1989. Physica C 162-164 (1989). D.L. Kaiser, F. Holtzberg, M.F. Chisholm, T.K. Worthington, J. Cryst. Growth 85 (1987) 593. W.K. Kwok, U. Welp, G.W. Crabtree, K.G. Vandervoort and J.Z. Liu (to be published). R.P. Huebener, Motion of Magnetic Flux Structures, in: Non Equilibrium Superconductivity, Phonons, Kapitza Boundaries, K.E. Gray ed. (Plenum Press, New York) (1981) p. 621.
242-244
FLUX FLOW RESISTIVITY W.K. KWOK, Materials
U. WELP.
Science
Division.
IN SINGLE CRYSTAL
G.W. CRABTREE,
Argonne
National
K.G.
Laboratory,
YBa,Cu,O,_, VANDERVOORT’ Argonne,
and J.Z.
LIU
IL 60439. USA
AC magnetoresistance measurements were performed on twinned single crystals of YBa,Cu,O,_, to study the effect of dissipative flux flow motion due to Lorentz force. We report the first direct observation of Lorentz force induced flux flow resistivity in high-T, superconductors which varies as sin’(e) with respect to transport current-magnetic field orientation. However, the intrinsic broadening of the resistive transition in magnetic field exists even in the absence of Lorentz force and hence cannot be explained by flux flow dissipative resistivity.
1. Introduction The anomalous broadening of the resistive transition in finite magnetic field in the high-T, superconductors is an important unresolved question. This behavior has been attributed to flux motion [ 1,2], field dependence of the critical current in Josephson junctions [3] (perhaps in the twinning planes) and fluctuation conductivity [4]. Thermally activated flux creep models [5] have been used to qualitatively explain the appearance of resistance in a field from dissipation of energy due to movement of vortices. In order to investigate whether the dissipative flux flow resistance is due to the transport current induced Lorentz force, a simple test can be applied to magnetoresistive measurements involving transport current(l)-magnetic field (H) geometries where H I( I gives zero Lorentz force and H I I induces maximum Lorentz force. So far, experiments [6] conducted on the high-T, superconducting films and single crystals with such currentfield geometries have yielded no apparent differences. Therefore, the explanation for the resistive broadening in magnetic fields based on flux flow phenomena is suspect. To address these issues quantitatively, we recently [7] measured ac magnetoresistivity on a high quality single crystal of YBa,Cu,O,_, in various current-field geometries to study the effect of Lorentz force on vortex motion. We found for the first time that the shape of the superconducting resistive transition curve in field for our YBa,Cu,O,_, single crystals is dependent on the current-field geometry. In this paper we follow up on our earlier measurements and include results on the angular dependence of the
magnetoresistance with respect to current-field etry which show the effect of Lorentz force flux flow resistivity in YBa,Cu,O, fi
geominduced
2. Experiment Single crystals of YBa,Cu,O,_, were prepared by a partial melting method described elsewhere [8]. Many crystals are produced in a single batch processing and exhibit sharp transitions with T, > 90 K. These crystals are platelets in shape with average dimensions of 0.05 X 2 X 3 mm’. AC resistivity was measured on two of these crystals by the standard four wire method with a measuring current of 0.1 mA at 17 Hz in fields up to 8 T. Current and voltage electrical leads were attached onto the a-b plane of the crystal with silver paint. Magnetic fields up to 8T were applied in the a-b plane of a single crystal at either parallel, perpendicular, or 30” off parallel geometry from the transport current direction. The parallel geometry leads to zero Lorentz force on the vortices by the transport current whereas the perpendicular geometry leads to maximum Lorentz force acting on the vortices. In addition, the 30” current-field angle geometry yields an intermediate Lorentz force value. In a second single the angular crystal of YBa,Cu,O,_, , we measured dependence of the flux flow resistivity by varying the angle between the transport current and the magnetic field in fixed field and temperature in the supeconductive resistive transition region.
3. Results and discussion
’ Also at University Partially Argonne
of Illinois at Chicago, Chicago, supported by Division of Educational National Laboratory.
OY21-4526/90/$03.50 (North-Holland)
0
Elsevier
Science
Publishers
IL 60680. Programs,
B.V.
Figure for three
la shows the resistivity current-field geometries
versus temperature in a magnetic field
243
W. K. Kwok et al. I F[ux flow resistivity in single crystal YBa,Cu,O,_,
Q 50 Experimental Data 0
89.0
91 .o
90.0
’ ’ ’s’ ’ -50 0
0.5
92.0
T(K) 200
. , . - I
. , - I . - .
sin’(e)
’
’ 50
3’ ’ ’ 1’ ’ 3’ ’ ’ ’ ’ ’ 3’ ’ ’ 100
150
200
250
angle
I 8 . . . ’
Fig. 2. Resistance versus current-field orientation angle at T = 91.22 K and H = 1.5 T. The solid line shows a fit to sin% behavior.
Fig. 1. (a) Resistivity versus temperature at 8 T for III H, I I H, and I at 30” from H. (b) Same as above with H = 2 T.
of 8T. The difference between the three curves demonstrates the evolution of flux flow resistivity with respect to current-field geometry. The transverse (H I I) geometry has the highest resistance value whereas the longitudinal (H I] I) geometry shows the lowest resistance values consistent with a flux flow resistivity induced by the Lorentz force on the vortices. A temperature sweep with magnetic field oriented 30” with respect to the transport current yields a resistivity curve lying between the transverse and longitudinal geometry resistivity curves. The zero resistance temperature signalled by an abrupt drop in resistivity at 89.1 K is the same for all three curves and hence independent of the current-field orientation. Figure lb shows the same measurement in a field of 2 T. The flux flow excess resistivity is less pronounced here than in the 8 T curves due to the lower magnetic field but the abrupt drop in resistivity at low temperatures is also evident. Both the 8 and 2T results show that the zero resistance temperature is independent of the current-field orientation within our experimental temperature resolution. Other single twin domain and
untwinned single crystals [9] exhibit a monotonic decrease to zero resistance, but the zero resistance temperature remains independent of the current-field orientation. The differences in the shape of the resistive transition curves among different samples are probably due to sample dependent pinning characteristics. Figure 2 shows the angular dependence of the resistance with respect to the current-field orientation. The data was taken on a second single crystal of in the superconducting resistive transiYBa,Cu,O,_, tion region at a fixed temperature of T = 91.22 K in a constant magnitude of a magnetic field of H = 1.5 T while varying the magnetic field direction with respect to the transport current direction. The result demonstrates that the dissipative resistance follows a sin% periodicity as expected from Lorentz force dissipation
[lOI. Our measurements show that Lorentz force induced flux motion manifests itself as excess resistivity in the superconducting resistive transition in finite magnetic field and follows a sin% dependence with respect to current-field orientation. This excess resistivity due to flux flow only affects the shape of the resistive transition and cannot account for the inherent broadening in the resistive transition in a magnetic field as proposed by Tinkham [l] since the zero resistance temperature in a finite field remains apparently unchanged. Therefore, the anomalous broadening of the resistive transition in a finite field seen even in the absense of a Lorentz force in the high-T, superconductors cannot be explained by a flux flow model and may be an intrinsic property of the material which must be investigated at a more microscopic scale.
244
W. K. Kwok
et al.
I Flux flow resistivity
in single crystal
Acknowledgements This work was supported by the US Department of Energy, Basic Energy Sciences-Materials Science contract #W-31-109-ENG-38 (WKK, GWC, JZL) and the National Science Foundation, Office of Science and Technology Centers under contract #STC-8809854 (VW, KGV), Science and Technology Center for Superconductivity, University of Illinois, UC).
[6]
References [7]
Ill M. Tinkham, Phys. Rev. Lett. 61 (1988) 1658. PI T.T.M. Palstra, B. Batlogg, L.F. Schneemeyer and J.V. Waszczak, Phys. Rev. Lett. 60 (1988) 1662. [31 D. Browne and B. Horowitz, Phys. Rev. Lett. 61 (1988) 1259. M.A. Dubson, S.T. Herbert, J.J. Calabrese, D.C. Harris, B.R. Patton and J.C. Garland, Phys. Rev. Lett. 60 (1988) 1061. [41 B. Oh, K. Char, A.D. Kent, M. Naito, M.R. Beasley, T.H. Geballe, R.H. Hammond, A. Kapitulnik and J.M. Graybeal, Phys. Rev. 37 (1988) 7861. Macroscopic MagPI For a review, see A.P. Malozemoff,
[8] [9] [lo]
YBa,Cu,O,_,
netic Properties of High Temperature Superconductors, in: Physical Properties of High Temperature Superconductors, D. Ginsberg, ed. (World Scientific, Singapore, 1989). K. Kitazawa, S. Kambe, M. Naio, I. Tanaka and H. Kojima (pre-print). H. Iwasaki, N. Kobayashi, M. Kikuchi, S. Nakajima, T. Kajitani, Y. Syono and Y. Muto (pre-print). N. Kobayashi, H. Iwasaki, H. Kawabe, K. Watanabe, H. Yamane, H. Kurosawa, H. Masumoto, T. Hirai and Y. Muto (pre-print). K.C. Woo, K.E. Gray, R.T. Kampwirth, J.H. Kang, S.J. Stein and R. East (pre-print). W.K. Kwok, U. Welp, G.W. Crabtree, K.G. Vandervoort and J.Z. Liu, Proc. Int. Conf. on Materials and Mechanisms of Superconductivity: High-Temperature Superconductors, Stanford, CA, July 23-28, 1989. Physica C 162-164 (1989). D.L. Kaiser, F. Holtzberg, M.F. Chisholm, T.K. Worthington, J. Cryst. Growth 85 (1987) 593. W.K. Kwok, U. Welp, G.W. Crabtree, K.G. Vandervoort and J.Z. Liu (to be published). R.P. Huebener, Motion of Magnetic Flux Structures, in: Non Equilibrium Superconductivity, Phonons, Kapitza Boundaries, K.E. Gray ed. (Plenum Press, New York) (1981) p. 621.