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CHINESE JOURNAL OF LOW TEMPERATURE PHYSICS

Vol.26   No.2   May,  2004

¡¡

CONTENTS

Nonlinear Response of Mixed State of Superconductors¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­

¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­NING  ZHEN£­HUA,¡¡CHEN KAI-XUAN,  WANG FU-REN,  YIN DAO-LE  (89)

Preparation and Thermoelectric Properties of Ce(Ni_1-xCu_x)₂Al_{3¡­¡­¡­}LU QING-FENG,

 ¡­¡­¡­WANG YAN-WEN,  HUO DE-XUAN,  SUN PEI-JIE,  ISIKAWA YOSIKAZU, SAKURAI JUNJI  (94)

Defect Properties of the La_0.7Sr_0.3MnO₃  Epitaxial Films are Studied by a Variable

 Energy Positron Beam¡­¡­¡­¡­¡­¡­¡­¡­  JIN SHAO-WEI,  GU WEI-WEI,  ZHOU XIAN-YI,

¡­¡­¡­WU WEN-BIN,  WENG HUI-MIN,  ZHU CHANG-FEI,  YE BANG-JIAO,  HAN RONG-DIAN  (100)

Magnetoresistance analysis of Sr₂RuO₄ near Superconducting Transition

Temperature¡­¡­¡­¡­¡­¡­LIU YA-JIANG,  LUO JIAN-LIN,  CHEN ZHAO-JIA,  WANG WAN-LU  (106)

A Compact High temperature Superconducting Narrowª²band Bandpass Filter

¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­ CHEN JING,  SUN LIANG,  LI SHUN-ZHOU,  HUANG JIAN-DONG,

     YIN ZHENG-CHAO,  HE AI-SHENG,  LI CHUN-GUANG,  ZHANG XUE-QIANG,  LI HONG,

  LUO SHENG,  GU CHANG-ZHI,  JIN AI-ZI,  YANG HAI-FANG,  FENG JI,  HE YU-SHENG     (111)

Experimental Investigation on dc Flow Suppression and Refrigeration

Characteristics of a High Performance Single stage GM type PTC¡­¡­¡­¡­¡­¡­

¡¡¡¡¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­ JIANG YAN-LONG,  CHEN GUO-BANG,  GAN ZHI-HUA,  G.THUMMES¡¡(119)

Influence of Low Er Doping (0.0¡Üx¡Ü0.20) on Transport Behavior in

La_0.67Sr_0.33MnO_{3¡­¡­¡­¡­¡­¡­¡­¡­}PENG ZHEN-SHENG,  LIU NING,  XU SHU-JUN,  TONG WEI  (125)

Lattice Effects on Low Fields Magnetoresistance in  Polycrystalline

La_0.7-xCe_xCa_0.3MnO_{3¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­}

¡­¡­¡­¡­ LI YAN-FEI,  ZHANG GUANG-YU,  GUI TAI-LONG,  WANG YI-JIE,  SONG WEI   (130)

The lifetime of metastate in Bose-Einstein Condensates¡­¡­¡­¡­¡­¡­¡­¡­¡­

    ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­  ZHAO HUA,  LIANG JIU-QING  (134)

Devices and Measurement Techniques in Cryo-shock Compression Experiments

¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­SUN YUE,

  YUAN CHANG-YING,  ZHANG XIU-LU,  LIU FU-SHENG,  WU GUO-DONG,  YANG XIANG-DONG (144)

Ballistic Transport and High T_c Superconductivity¡­¡­LIU LONG-JIAN,  GAO JIE (154)

Spin Transport Property in La_0.825Sr_0.175MnO₃ Film¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­

¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­JIN KE-XIN,  CHEN CHANG-LE,  WANG YUE-LONG,

  ZHAO SHENG-GUI,  WANG YONG-CANG,  WANG SHI-LIN,  YUAN XIAO,  SONG YU-MO  (159)

Study the Effection on Double Body in Superconductors¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­

¡¡¡¡¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­CHEN YU,  HUANG XIN-MIN  (163)

Differential Conductance In Differential Conductance in the Normal¡¡

Metal/d_x2-y2+id_xy Mixed Wave Superconductor Tunnel Junctions¡­ WEI JIAN-WEN  (169)

Optimization and Size Effects of NbTi Solenoids for Smes¡­¡­¡­¡­NAN HE-LI  (176)

³¬µ¼»ìºÏ̬µÄ·ÇÏßÐÔÏìÓ¦

ÄþÕñ»ª  ³Â¿­Ðý  Íõ¸£ÈÊ  ÒüµÀÀÖ

±±¾©´óѧÎïÀíѧԺ£¬ ±±¾©  100871

ÔÚÏà±äÁÙ½çµã¸½½üµÄ·ÇÏßÐÔÏìÓ¦º¯ÊýÆÕ±é×ñÊØÃÝÂÉ.ËüÈçºÎÓëÏà±äÁ½·½µ¥¸öÔÈÏàµÄÎïÐÔÏàÁª½áµÄÎÊÌâÉÐδµÃµ½ºÜºÃµÄ½â¾ö.±¾Îĸø³öÒ»¸ö´Ó¸ßÎÂϵÄÕý³£Ì¬µ½µÍÎÂϳ¬µ¼»ìºÏ̬µÄµç×èת±ä·½³Ì.ËüÓëMgB₂ºÍYBaCuOʵÑéÊý¾Ý·ûºÏµÃºÜºÃ£¬²¢ÄܽâÊͶàÄêÁîÈËÀ§»óµÄ½»Á÷ºÄÉ¢ÏìÓ¦·åÖµµÄÕñ·ùЧӦ.±¾ÎÄ»¹½øÒ»²½ÌÖÂÛÁËÓë´ËÏàËƵġ°À©Õ¹ÃÝÂÉ¡±ÐÍ·ÇÏßÐÔÏìÓ¦º¯ÊýÓ¦ÓÃÓÚÆäËûÏà±äÁÙ½çÏÖÏóµÄÎÊÌâ.

¹Ø¼ü´Ê£º»ìºÏ̬, ½»Á÷ºÄÉ¢·å, ±ê¶ÈÂÉ, ·ÇÏßÐÔÏìÓ¦º¯Êý

PACC:   6460, 7430F, 7460E, 3520M

 NONLINEAR RESPONSE OF MIXED STATE OF SUPERCONDUCTORS

NING ZHEN£­HUA ¡¡CHEN KAI-XUAN   WANG FU-REN  YIN DAO-LE

Department of Physics, Peking University, Beijing 100871

The nonlinear response functions near critical points often take the form of power law. Their relation to the homogeneous phases in both sides of transition still remains to be resolved. We show a resistive transition equation between normal and superconducting mixed states which well fits the experimental data of MgB₂ and YBCO. It also reasonably explains the puzzling amplitude-dependent peak of ac usceptibility ¦Ö¡å. The applicability of similar ¡°extended power law¡± nonlinear response for other kinds of phase transition is also discussed.

Keywords: mixed state, the amplitude of ac susceptibility, scaling, nonlinear response function

PACC:     6460, 7430F, 7460E, 3520M

½ðÊô¼ä»¯ºÏÎïCe(Ni_1-x Cu_x)₂Al₃µÄÖƱ¸ºÍÈȵçÌØÐÔ

·Çì·ï¹  ÍõÑÞÎĹ  »ôµÂ诲  ËïÅà½Ü³  ʯ´¨ÒåºÍ³  Ó£¾®´¼ƒ¹³

¹ºÓÄÏʦ·¶´óѧÎïÀíÓëÐÅÏ¢¹¤³ÌѧԺ, ºÓÄÏÐÂÏç  453002

²¶«»ª´óѧ²ÄÁÏ¿ÆѧÓ빤³ÌѧԺ£¬ÉϺ£  200051

³ÈÕ±¾¸»É½´óѧÀíѧ²¿£¬ÈÕ±¾  9308555

ÎÒÃÇÒÔCuÌæ´úNi£¬ÖƱ¸Á˽ðÊô¼ä»¯ºÏÎïCe(Ni_1-xCu_x)₂Al₃(x=0.0,0.1,0.2,0.3,0.4)£¬ÀûÓ÷ÛÄ©XÉäÏßÑÜÉä·¨£¨XRD£©¶ÔÑùÆ·½øÐÐÁ˱íÕ÷.µç×èÂʦѣ¨T£©ºÍÈȵçÊÆS£¨T£©²âÁ¿½á¹û±íÃ÷£¬ÓÉÓÚCuÌæ´úNiʹµÃµ¥°ûÌå»ýºÍ3d´«µ¼µç×ÓÊýÄ¿Ôö¼Ó£¬4fµç×ÓÓë´«µ¼µç×ÓÖ®¼äµÄÔÓ»¯¼õÈõ.½üÌÙζÈT_KËæ×ÅxµÄÔö¼Ó¶ø½µµÍ£¬ÌåϵÇ÷ÓÚÐγÉÖصç×Óϵͳ.

¹Ø¼ü´Ê£º½ðÊô¼ä»¯ºÏÎ ÈȵçÊÆ£¬ µç×èÂÊ£¬ ·ÛÄ©XÉäÏßÑÜÉ䣬 Ce(Ni_1-xCu_x)₂Al₃, Öصç×Óϵͳ

PACC:   7127, 7128, 7215J

PREPARATION AND THERMOELECTRIC

 PROPERTIES OF Ce(Ni_1-xCu_x)₂Al₃

LU QING-FENG¹  WANG YAN-WEN¹  HUO DE-XUAN²  SUN PEI-JIE³  ISIKAWA YOSIKAZU³  SAKURAI JUNJI³

¹College of Physics & Information Engineering, Henan Normal University,  Xinxiang 453002

²College of Material Science And Engineering, DongHua University, Shanghai  200051

³Department of Physics, Toyama University, Toyama, 930ª²8555, Japan

By partially substituting Ni with Cu, we prepared intermetallic compounds

Ce(Ni_1-xCu_x)₂Al₃(x=0.0, 0.1, 0.2, 0.3, 0.4). We determined the structure of the samples using powder X-ray diffraction, and measured the electrical resistivity ¦Ñ(T) and thermoelectric power S(T). The results reveal that the increase of unit-cell volume and the number of 3d electrons results in the weakened hybridization between 4f and conduction electrons by introducing Cu atoms into the Ni sites. With increasing the Cu concentration x, the Kondo temperature T_K decreases, and the system tends to form heavy electronic compound.

Keywords: Intermetallic compounds, thermoelectric power, Electrical resistivity, Powder X-ray diffraction, Ce(Ni_1-xCu_x)₂Al₃, heavy electronic compound

PACC: 7127£¬ 7128£¬ 7215J

La_0.7Sr_0.3MnO₃ÍâÑÓĤȱÏÝ

ÐÔÖʵÄÂýÕýµç×ÓÊøÑо¿

½ðÉÜά¹  ¹Ëΰΰ¹  ÖÜÏÈÒâ¹  ÎâÎıò²

ÎÌ»ÝÃñ¹  Ö쳤·É³    Ò¶°î½Ç¹    º«ÈÙµä¹

¹Öйú¿Æѧ¼¼Êõ´óѧ½ü´úÎïÀíϵ£¬ºÏ·Ê  230027

²Öйú¿Æѧ¼¼Êõ´óѧ½á¹¹·ÖÎöÖصãʵÑéÊÒ£¬ºÏ·Ê  230026

³Öйú¿Æѧ¼¼Êõ´óѧ²ÄÁÏ¿ÆѧÓ빤³Ìϵ£¬ºÏ·Ê  230026

Óõ¥ÄÜÂýÕýµç×ÓÊø,²âÁ¿Á˲»Í¬Ñõ·ÖѹÏÂÉú³¤µÄLa_0.7Sr_0.3MnO₃ÍâÑÓĤµÄS²ÎÊýÓëÈëÉäÕýµç×ÓÄÜÁ¿EµÄ¹Øϵ.½á¹û·¢ÏÖLa_0.7Sr_0.3MnO₃ÍâÑÓĤÖÐS²ÎÊýÓëÑõ·ÖѹÊǷǵ¥µ÷±ä»¯µÄ£»ÕâÓë³Á»ýÑõ·ÖѹµÄÁ½ÖÖ×÷ÓÃÏà¹ØÁªµÄ.ÔÚÑõ·Öѹ½Ï¸ßµÄLSMO±¡Ä¤ÖÐ, ¿ÕλŨ¶ÈµÄÔö¼ÓÖ÷ÒªÊÇÓɳÁ»ýÔ­×Ó£¨Àë×Ó£©ÓëÑõÔ­×ÓÅöײ¼¸ÂÊÔö´ó,ʹÆäȱ·¦×ã¹»µÄ¶¯ÄÜÈ¥Ìî²¹¿ÕλÒýÆðµÄ£»ÔÚµÍÑõ·ÖѹµÄLSMO±¡Ä¤ÖÐ, ¿ÕλŨ¶ÈµÄÔö´óÔòÖ÷ÒªÊÇÌṩ³ÉĤËùÐèÒªµÄÑõÔ­×Óȱ·¦£¬´Ó¶øµ¼ÖÂÑõ¿Õλ¼°ÆäÏà¹ØȱÏÝÔö¼Ó.

¹Ø¼ü´Ê£ºÈ±ÏÝÐÔÖÊ£¬ ÍâÑÓ±¡Ä¤£¬ Ôöµç×ÓäÎÃð

PACC£º  7570£¬ 7870

DEFECT PROPERTIES OF THE La_0.7Sr_0.3MnO₃

EPITAXIAL FILMS ARE STUDIED BY

A VARIABLE ENERGY POSITRON BEAM

JIN SHAO-WEI  GU WEI-WEI  ZHOU XIAN-YI WU WEN-BIN

WENG HUI-MIN  ZHU CHANG-FEI  YE BANG-JIAO  HAN RONG-DIAN

¹Department of Modern Physics, University of Science and Technology of China, Hefei 230027

²Structure Research Laboratory, University of Science and Technology of China, Hefei 230026

³Department of Materials Science and Engineering, University of Science

and Technology of China, Hefei 230026

(Received  15 October, 2003)

By using a variable energy positron beam system, the linear S parameter as a function of implantation positron energy was measured on the epitaxial La_0.7Sr_0.3MnO₃ thinfilms from different deposition oxygen pressures. It is found that the relationship between the S parameters of the epitaxial La_0.7Sr_0.3MnO₃ films and oxygen pressures is not monotonous. This relationship is related to the actions of the deposition oxygen pressure. For the La_0.7Sr_0.3MnO₃ film was prepared by the high growth oxygen pressure, the increase of the vacancy concentration is caused from the large collision faction of the deposition atom and oxygen atom. In contrast, for the film prepared by the low growth oxygen pressure, the increase of the vacancy concentration is caused from the oxygen atom deficiency during the film growth and resulted in the oxygen vacancies and the related defect complexes.

Keywords: defect properties, epitaxial films, positron annihilation

PACC:     7570, 7870b

Sr₂RuO₄³¬µ¼×ª±äζȸ½½üc·½Ïò´Å×èÐÐΪÑо¿

ÁõÑǾ²^1,2   öý¨ÁÖ²  ³ÂÕ׼ײ  ÍõÍò¼¹

¹ÖØÇì´óѧӦÓÃÎïÀíϵ£¬ÖØÇì  400044

²Öйú¿ÆѧԺÎïÀíÑо¿Ëù£¬±±¾©  100080

²âÁ¿ÁËSr₂RuO₄Õý³£Ì¬ºÍ³¬µ¼×ª±äζȸ½½ü£¨T=1.5K, 4.0K, 6K£©c·½ÏòµÄ´Å×裬ͨ¹ý¶ÔÕý³£Ì¬´Å×è·ÖÎö»ñµÃÁËSr₂RuO₄ÔÚζÈ4KºÍ6KϵÄƽ¾ù×ÔÓɳÌ.ͨ¹ý³¬µ¼ÕÇÂä·ÖÎö»ñµÃÁËSr₂RuO₄µÄ³¬µ¼ÌØÐÔ²ÎÊý¦Î_ab(0)ºÍ¦Î_c(0).

¹Ø¼ü´Ê£º³¬µ¼ÕÇÂ䣬 ´Å×裬 Ïà¸É

PACC:   0540, 7530V, 4210M

MAGNETORESISTANCE ANALYSIS

OF Sr₂RuO₄  NEAR SUPERCONDUCTING

TRANSITION TEMPERATURE

LIU YA-JIANG  LUO JIAN-LIN  CHEN ZHAO-JIA  WANG WAN-LU

¹Department of Applied Physics, Chongqing University, Chongqing 400044

²Institute of Physics, Chinese Academy of Sciences, Beijing 100080

£¨Received 15 October ,2003£©

We report a detailed study of the c axis magnetoresistance near superconducting transition temperature in Sr₂RuO₄, the layered perovskite superconductor which does not contain copper. By the analysis of the normal state magnetoresistance we have obtained the in plane mean free path. A large positive magnetoresistance near T_c  has been observed, which is originated from superconducting fluctuations. The fluctuation-enhanced magnetoconductivity very close to T_c shows well agreement with Aslamasov-Larkin(AL) prediction for a 2-D superconductor, and the coherence lengths of Sr₂RuO₄, have been deduced from fluctuation magnetoresistance analysis at 1.5K.

Keywords: superconducting fluctuation, magnetoresistance

PACC:     0540, 7530V, 4210M

Ò»Öֽṹ½ô´ÕµÄ¸ß㬵¼Õ­´ø´øͨÂ˲¨Æ÷

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Àè  ºì¹  ÂÞ  ʤ²  ¹Ë³¤Ö¾¹  ½ð°®×Ó¹

Ñ·½¹  ·ë  𢹠 ºÎÔ¥Éú¹

¹Öйú¿ÆѧԺÎïÀíÑо¿Ëù£¬ ±±¾©  100080

²±±¾©¿Æ¼¼´óѧÎïÀíϵ£¬ ±±¾©  100083

³Öйú¿ÆѧԺÉùѧÑо¿Ëù£¬ ±±¾©  100080

ÑÐÖÆÁËÒ»Öֽṹ½ô´ÕµÄ¸ß㬵¼Õ­´øÂ˲¨Æ÷.¸ÃÂ˲¨Æ÷ÖÐÐÄƵÂÊΪ£¬ÊÇÔÚÒÔ0.5mmºñµÄLaAO₃(¦Å_r¡Ö24)Ϊ³Äµ×µÄYBCO³¬µ¼±¡Ä¤ÉÏÖÆ×÷µÄ.²âÊÔ½á¹ûÏÔʾ¸ÃÂ˲¨Æ÷¾ßÓбȽϺõÄÐÔÄÜ£¬Æä²åÈëËðºÄ<0.3dB£¬·´ÉäËðºÄ<-16dB£¬Ïà¶Ô´ø¿í<9¡ë, ´ø±ß¶¸¶È>9dB/MHz, ÖÐÐÄƵÂÊÎó²î<0.05%.Â˲¨Æ÷Éè¼ÆÖУ¬ÀûÓÃÌØÊâ¼¼Êõ³É¹¦µØ¸ÄÉÆÁ˹ý¶É´øÉϵÄÁãµãÌØÐÔ£¬Îª½ñºóÑÐÖÆÐÂÐ͵Ľṹ½ô´ÕµÄÂ˲¨Æ÷¿ªÍØÁË˼·.

¹Ø¼ü´Ê£º¸ß㬵¼£¬ ΢²¨Ó¦Ó㬠´øͨÂ˲¨Æ÷

PACC:   7470V, 7870G, 4280C

A COMPACT HIGH-TEMPERATURE

SUPERCONDUCTING NARROW-BAND

BANDPASS FILTER

CHEN JING   SUN LIANG   LI SHUN-ZHOU   HUANG JIAN-DONG

YIN ZHENG-CHAO   HE AI-SHENG   LI CHUN-GUANG   ZHANG XUE-QIANG   LI HONG

LUO SHENG   GU CHANG-ZHI   JIN AI-ZI   YANG HAI-FANG   FENG JI   HE YU-SHENG

¹Institute of Physics, Chinese Academy of Sciences, Beijing  100080

²Department of Physics, University of Science and Tecnology, Beijing  100083

³Institute of Acoustics, Chinese Academy of Sciences, Beijing  100080

£¨Received 15 October, 2003£©

A compact high-temperature superconducting narrow-band bandpass filter was fabricated. The filter was designed to have a center frequency 1725MHz, and fabricated using double-side-coated YBCO thin film on a 0.5mm-thick lanthanum aluminate substrate (¦År¡Ö24). An encouraging performance has been achieved. The measured responses of the filter showed a insertion loss of <0.3dB, a return loss of <-16dB in the filter passband£¬ a fractional bandwidth of <9¡ë, and a steepness better than 9dB/MHz. The deviation of the central frequency is smaller than 0.05%. A pair of transmission zeros located at both sides of the passband were introduced with a special technique in designing, which has greatly improved the frequency response characteristics of the filter and can be used as a helpful new method in future compact bandpass filter design.

Keywords: HTS, microwave applications£¬ bandpass filter

PACC:     7470V, 7870G, 4280C

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PACC£º  0720M

EXPERIMENTAL INVESTIGATION ON

DC FLOW SUPPRESSION AND REFRIGERATION

CHARACTERISTICS OF A HIGH-PERFORMANCE

SINGLE-STAGE GM-TYPE PTC

JIANG YAN-LONG   CHEN GUO-BANG   GAN ZHI-HUA   G.THUMMES

¹Department of Man-Machine and Environment Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing  210016

²Cryogenics laboratory, Zhejiang University, Hangzhou 310027

³Institute of Applied Physics, University of Giessen 35392, Germany

(Received  5 August, 2003; revised manuscript received  19  November, 2003)

Experimental investigation on DC flow suppression and refrigeration characteristics of a high-performance single-stage GM-type pulse tube cooler has been undertaken in this paper. The influence of DC flow induced by the introduction of double-inlet on the refrigeration performance of the cooler is experimentally examined. Two parallel-placed needle valves with opposite flow direction called as double-valved configuration, instead of conventional single-valved configuration as the double-inlet is successfully used in this experiment to reduce the DC flow. Besides, the performance of the cooler with various regenerator matrices and supply power of compressors has been extensively investigated under different operation modes. Operating under double-inlet mode, 18.4K and 14.7K minimum temperature has been reached driven by RW2 and CP4000 compressor respectively, and 11.5W and 29.5W cooling power at 30K have been obtained as well.

Keywords: High-performance, pulse tube cooler, DC flow

PACC:     0720

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