Gupta, A K

Swarup, Ram

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Indian J. Phys. 73A (5). 633-638 (1999)U P  A‘ an  in te rna tiona l loum alDependence of microwave surffice impedance on crystallographic orientationin YBa2 Cu3 0 7 _x thin filmsRam Swarup and A K GuptaN a tio n a l P h y s ic a l L a b o ra to ry , D r. K S K rishn im  R oad ,N ew  D e lh i-1 1 0  0 1 2 , In d iaReceived 31 December 1998, accepted 12 April 1999A b s t r a c t  : W e  re p o r t th e  v a ria lio n  o f  m ic ro w a v e  su rfa c e  re s is ta n c e  (/?^) and  re s id u a l p e n e tra tio n  d e p th  A(0) o f  Y B C O  th in  film s as a fun c tio n  o f  o n e n ta tio n  o f  the  film s T h ree  thin film  s a m p le s  A , B an d  C  h a v e  b e en  s tu d ie d . A s re v ea led  th ro u g h  X R D  pa tte rn s , film  A is p a rtia lly  c -a x is  o r ie n te d , f ilm  B has  b e tte r  c -ax is  o rien ta tio n  w h ile  film  C  is fu lly  r-ax is  o rien ted  T h e  m o d if ied  e n d  p la te  re p la c em e n t tech n iq u e  o p era tin g  at 10 G H z  in T E qi i m ode and sapph ire  lo a d e d  d ie le c tr ic  re s o n a to r  te c h n iq u e  o p e ra tin g  at 13 6 G H z  in T E o i^  m ode  w ere  used  fo r the  m e a su re m e n t o f  R^  an d  A (0). T h e  v a lu e  o f  7?^  (13  6  G H z, 65 K ) fo r sam p les  A, B and  C have b een  fo u n d  to  be  1.607, 1 3 5 6  an d  1 037  m U  resp ec tiv e ly  L o w er va lues of R,. (65  K ) = 930, 780  and  6 0 0  p l l  h av e  b e en  m easu red  ai 10 G H z  fo r  these  film s. T he  va lues o f  A(0) (13 .6  G H /)  have b een  fo u n d  to  be 1950, 1830 an d  16.50 A fo r the  film s A, B and  C  respec tive ly . As the deg ree  o l o r ie n ta tio n  o f  i -ax is  g ra in s  in c rea se s  in th in  film s, the  Jo sep h so n  cou p lin g  ge ts  s tro n g er and the v a lu e  o f  R^  an d  A(0) d ec rea ses .K e y w o r d s  : M ic ro w av e  su rface  re s is tance , Y B C O  th in  film s, gram  o n en ta tio n  PACS N o s. : 7 8 .7 0 .G q , 7 4  2 5 .N f1. IntroductionThe crystallographic defects in metallic conductors have been a source of power loss from dc to electromagnetic wave frequencies and their control with the increase of purity from 99.5-99.9995% for hyperconductors accompanied by large increase in the resistivity ratio P (300 K)/p (20 K) from 50-6000 is reported in the literature. LowT, metallic superconductors with low values of (10 GHz) » 25 |iit2 and A(0) = 1400 A at liquid helium temperature have however been in use in microwave superconducting electronics for quite some time. With the discovery of high-T .^ cuprate superconductors* various studies have been conducted on YBCO ceramic material processed under different conditions and© 1999 I ACS636 Ram Swamp and A K Guptawhereas in the sample B, the intensity of the 113, 116/123 and 213 peaks diminish and peaks corresponding to the 103/110 and (OOn) planes only appear. The film C contains peaks corresponding to (OOn) planes only. Film A is partially c-axis oriented, film B has better c-axis orientation while film C is fully c-axis oriented. Other characteristics of the samples arc given in the Table 1. The variation of /?, of the samples with temperature atTable 1. Characteristics of the samplesSamples A B CTc(K) 87 88 90ATc(K) 1 7 1 5 1 4R, (10 GHz, 65 930 780 600R, (1.^6 GHz, 65 K)(mn) 1 607 1.356 1037A(0)(I3 6GH/)(A) 1950 1830 16.5010 GHz is given in Figure 2 whereas the corresponding results at 13.6 GHz are shown in Figure 3. The rate of fall of the microwave surface resistance {dR,/dT) }us\ below Tc hasTEMPCRATuaetK)Figure 2. Variation of (10 GHz) of the samples with temperature.Figure 3. Variation of (13.6 GHz) of the samples with temperature.been found to become steeper as the number of c-axi$ oriented grains increases in the film samples A to B to C and the value of /?, (65 K) has been found to be the lowest for the highly c-axis oriented sample C. The variation of the resonant frequency of the dielectric resonator with temperature is shown in Figure 4. The computed values of A(0) have been^n ce  of microwave superconductor'®Dependence oj , .  n m C. The hig'''^ c ^^inks.. thft A ^ josep^ s®^„irf»n»S»«“ ”“  ^ ___ — —  \r------tTZw:* film* \YBCO« « «  * • state is gi^"(4)44. <‘ ) y T « . n  -  W '" '“ ‘ “ " ' '■ '^ '1 ’4. c o » d » M »   ^ „  e o M  •»> W”' “ “  “ y ' X r o i  * « »-^ '“* °‘I i  w «'* *“ “? “ >»«>'• “ “ ’“X *r r s 4 - r - - : r r ^ ; ^ r “ -A\^ MX\ , rrxtiXlXctoo«ledpnent t. a  K R^ V i i^of. R P‘"‘°supp^ y'*'^638 Ram Swamp and A K GuptaReferences[1] G Muller, D J Brauer, R Eujen, M Hein, N Klein, H Piel, L Ponto, U Klein and M Peiniger IEEE Trans, Magn. 25 2402 (1989)[2] Q Li, K W Rigby and M S Rzchowski Phys. Rev. B39 6607 (1989)[3] A M Awasthi, J P Carini, B Alavi and G Gniner Solid State Commun. 67 373 (1988)[4] J Wosik. R A Krancnburg, J C Wolfe, V Selvamanickam and K Salama J, Appl Phys. 69 874 (1991)[5] Ram Swurup and A K Gupta Indian /  Pure Appl. Phys. 32 464 (1994)[6} A K Gupta, Ram Swamp and M C Bansal Physica C235-240 2(X)5 (1994)[7] Ram Swamp, A K Gupta and M C Bansal J, Supercond. 8 361 (1995)[8J N Klein, G Muller, S Orbach, H Piel, H Chaloupka, B Roas, L Schultz, U Klein and M Peiniger Physica C162-164 1549 (1989)[9] R Pinto, S P Pai, C P D'souza, L C Gupta, R Vijayaraghavan, D Kumar and M Sharon Physica C196 264 (1992)[10] R Chandra, A K Gupta and V Kumar Indian J, Pure Appl. Phys. 32 133 (1994)[11] C Le Paven-Thivet, M Guilloux-Viry, J Padiou, A Perrin, M Sergent, L A de Vaulchier and N Bontemps Physica C2A4 231 (1995)[12] X Y L i , N J Wu, K Xie, J S Liu. H Lin, T Q Huang and A Ignatiev Physica C248 281 (1995)[13] Ram Swamp, A K Gupta, S K Srivastava, V Kumar and M C Bansal Solid State Phys. (India) 38C 284(1995)[14] Ram Swamp, A K Gupta and M C Bansal Indian J. Cryog. 20 3 (1995)

Dependence of Microwave Surface Impedance on Crystallographic Orientation in YBa2Cu3O7-xThin Films

http://arxiv.iacs.res.in:8080/jspui/bitstream/10821/5724/1/Dependence%20of%20Microwave%20Surface%20Impedance%20on%20Crysta_Ram%20Swarup.pdf

Dependence of Microwave Surface Impedance on Crystallographic Orientation in YBa2Cu3O7-xThin Films

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