用溶胶-凝胶法制备La1-xCaxMn1.03O3(x=0.2,0.4)薄膜的庞磁电阻效应

报道了用溶胶－凝胶（sol-gel）方法在LaAlO3(100)衬底上制备La1-xCaxMn1.03O3(x=0.2,0.4)外延薄膜的方法和磁电阻效应。电阻率随温度的变化关系，是从类半导体行为向金属导电行为转变，对x=0.2样品，Tc最高达275K，Rm最大可达10^4％（B＝1．5T）。     

INFLUENCE OF PINNING CENTER DISTRIBUTION ON THE PINNING OF TWO-DIMENSIONAL VORTEX SYSTEM

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｐｈｙｓｉｃｓｏｆａｖｏｒｔｅｘｌａｔｔｉｃｅ (ＶＬ)ｉｎｔｙｐｅ ＩＩｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓｈａｓｂｅｅｎｔｈｅｆｏｃｕｓｏｆｉｎｔｅｒｅｓｔｓｉｎｃｅｔｈｅｂｅｇｉｎｎｉｎｇｏｆｈｉｇｈ Ｔｃ ｒｅｓｅａｒｃｈ .Ｉｔｉｓｗｅｌｌ ｋｎｏｗｎｔｈａｔ,ａｆｔｅｒｔｈｅｅｘｔｅｒｎａｌｍａｇｎｅｔｉｃｆｉｅｌｄｅｘｃｅｅｄｓｉｔｓｃｒｉｔｉｃａｌｖａｌｕｅＨｃ1 ,ｔｈｅｍａｇｎｅｔｉｃｆｉｅｌｄｃａｎｐｅｎｅｔｒａｔｅａｔｙｐｅ ＩＩｓｕｐｅｒｃｏｎｄｕｃｔｏｒｉｎ…     

POSITIVE MAGNETORESISTANCE IN NI/W SUPERLATTICES

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍａｇｎｅｔｉｃａｎｄｔｒａｎｓｐｏｒｔｐｒｏｐｅｒｔｉｅｓｏｆｔｈｉｎｍａｇｎｅｔｉｃｍｕｌｔｉｌａｙｅｒｓｈａｖｅａｔｔｒａｃｔｅｄｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎｄｕｒｉｎｇｔｈｅｐａｓｔｙｅａｒｓ.Ｓｉｎｃｅｄｉｓｃｏｖｅｒｙｏｆｎｅｇａｔｉｖｅｇｉａｎｔｍａｇｎｅｔｏｒｅｓｉｓｔａｎｃｅ (ＧＭＲ)ｂｙＢａｉｂｉｃｈｅｔａｌ.ｉｎＦｅ/Ｃｒｍｕｌｔｉｌａｙｅｒｓ (Ｂａｉｂｉｃｈ ,1 998) ,ｅｘｔｅｎｓｉｖｅｒｅｓｅａｒｃｈｈａｓｂｅｅｎｄｏｎｅｃｏｎ ｃ…     

PROPERTIES OF VORTEX SYSTEM WITH RANDOM COLUMNAR DEFECTS AT ZERO TEMPERATURE

ＩＮＴＲＯＤＵＣＴＩＯＮＴｙｐｅＩＩｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓｉｎａｓｕｆｆｉｃｉｅｎｔｌｙｓｔｒｏｎｇｍａｇｎｅｔｉｃｆｉｅｌｄｃｈａｎｇｅｔｏａｍｉｘｅｄｓｔａｔｅａｎｄａｖｏｒｔｅｘｌａｔｔｉｃｅ (ＶＬ)ｆｏｒｍｓ .Ｔｈｅｉｎｆｌｕｅｎｃｅｏｆｑｕｅｎｃｈｅｄｒａｎｄｏｍｐｉｎｎｉｎｇｓｏｎｔｈｅｖｏｒｔｅｘｌａｔｔｉｃｅｉｓａｓｕｂｊｅｃｔｏｆｌｏｎｇｓｔａｎｄｉｎｇｉｎｔｅｒｅｓｔ.Ｉｎａｐｐｌｉｃａ ｔｉｏｎｏｆｈｉｇｈ Ｔｃｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓｉｎｓｔｒｏｎｇｍａｇ ｎｅ…     

Pseudopotential generation

Different classes of first-principle pseudopotentials are compared and various schemes for pseudopotential generation based on norm conservation are discussed in this paper. BHS (Bachelet, Hamann, and Schlüter)-scheme and V (Vanderbilt)-modifications are used to derive the KB (Kleinman and Bylander)-pseudopotentials and pseudo wave functions of bismuth. Quality test of pseudopotentials shows that no ghost states occur in the logarithmic derivatives of pseudo wave functions of Bismuth. The obtained bond length of bismuth dimer with this type of pseudopotentials is in good agreement with previous accurately calculatedab initio quantum chemical result. Project supported by the Ministry of Science and Technology of China (NKBRSF-G19990646), the Postdoctoral Science Foundation of China, and the Scientific Research Foundation of State Education Ministry for Returned Overseas Chinese Scholars     

TRANSPORT PROPERTIES ON La_(0.7)Sr_(0.3)MnO_3/Al_2O_3/Fe TUNNEL JUNCTIONS

ＩＮＴＲＯＤＵＣＴＩＯＮＭｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｐａｉｄｒｅｃｅｎｔｌｙｔｏｔｈｅｓｔｕｄｙｏｆｓｐｉｎｐｏｌａｒｉｚｅｄｔｕｎｎｅｌｉｎｇｉｎｊｕｎｃｔｉｏｎｓｏｆｔｗｏｆｅｒｒｏｍａｇｎｅｔｓｓｅｐａｒａｔｅｄｂｙａｎｏｎｍａｇｎｅｔｉｃｔｕｎｎｅｌｉｎｇｂａｒｒｉｅｒ(Ｙａｏｉｅｔａｌ.,1993;Ｎｏｗａｋｅｔａｌ.,1992;Ｓｕｅｚａｗａｅｔａｌ.,1992;ＬｅＣｌａｉｒｅｔａｌ.,1994;Ｐｌａｓｋｅｔｔｅｔａｌ.,1994;Ｍｉｙａｚａｋｉｅｔａｌ.,1995;Ｔｅｚｕｋａｅｔａｌ.,1996).Ａｓｉｇｎｉ…     

Pseudopotential generation

ＩＮＴＲＯＤＵＣＴＩＯＮＳｉｎｃｅｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆｔｈｅｐｓｅｕｄｏｐｏｔｅｎｔｉａｌｍｅｔｈｏｄ (Ｐｈｉｌｌｉｐｓｅｔａｌ.,1 959) ,ａｎｄｔｈｅｓｕｂｓｅ ｑｕｅｎｔｐｒｏｏｆｏｆｔｈｅＰｈｉｌｌｉｐｓＣａｎｃｅｌｌａｔｉｏｎＴｈｅｏｒ     

A δ-function-like peak in the specific heat of two-dimensional vortex lattice: Monte carlo study

ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓ,ｔｈｅｒ ｍａｌ ｆｌｕｃｔｕａｔｉｏｎｅｆｆｅｃｔｓａｒｅｖｅｒｙｓｍａｌｌｂｅｃａｕｓｅｏｆｔｈｅｌａｒｇｅｃｏｈｅｒｅｎｃｅｌｅｎｇｔｈ .Ｍｅａｎ ｆｉｅｌｄｔｈｅｏｒｙ ,ｔｈｅｒｅｆｏｒｅ,ｃａｎｇｉｖｅａｇｏｏｄｄｅｓｃｒｉｐｔｉｏｎｏｆｔｈｅｓｅｓｙｓｔｅｍｓ.Ｉｎｃｏｎｔｒａｓｔ,ｂｅｃａｕｓｅｏｆｔｈｅｓｈｏｒｔｃｏｈｅｒ ｅｎｃｅｌｅｎｇｔｈｓａｎｄｌａｒｇｅａｎｉｓｏｔｒｏｐｙ ,ｔｈｅｒｍａｌｆ…     

Bipolaron in different configuration of quantum confinement

The authors used Landau-Pekar variational method to investigate a strong-coupling singlet optical bipolaron in different configuration of quantum confinement.Numerical and analytical results showed that when configuration changes from quantum dot and wire to well,confinement shows different effect on the formation of a bipolaron.In contrast to a bipolaron in a quantum dot or wire,the binding energy of a bipolaron in a quantum well increases with increasing confinement,indicating that confinement favors bipolaron formation in a quantum well.     

Bipolaron in different configuration of quantum confinement

INTRODUCTION The bipolaron in bulk materials has been ex-tensively discussed in the past decade. With morerecent advances in the creation of nanocrystal withstrong ionic coupling (Hudgins et al., 1997), onenatural problem is that the effect of bipolarons insome quantum low dimensional systems with ef-fective electron-phonon coupling is very strongowing to the confinement. This problem is alsorelevant to the proposal of the bipolaronic mecha-nism for pairing in CuO2 plane (quasi-tw…