Magnetic and transport properties of Nd0.2La1.8-2xSr1+2xMn2O7 (x = 0.5, 0.4, 0.3) and La1.5Sr1.5Mn2O7

Lattice structure, magnetic and transport properties of polycrystalline samples of Nd0.2La1.8-2xSr1+2xMn2O7 in the range 0.5≥x≥0.3 and La1.5Sr1.5Mn2O7 have been investigated. A pronounced decrease of the Curie temperature TC and the metal-insulator transition temperature TMI of Nd0.2La1.8-2xSr1+2xMn2O7 compared to Nd-free compounds La2-2xSr1+2xMn2O7 with the same doping level has been observed. The shift of TC, which is increased with decreasing Sr content, indicates a weakening of the ferromagnetic ordering for the Nd-substituted samples. Nd0.2La1.2Sr1.6Mn2O7 orders ferromagnetically at TC = 75 K and reveals a transition to an antiferromagnetic (afm) spin arrangement below TN = 38 K, whereas polycrystalline samples of the composition La1.4Sr1.6Mn2O7 remain ferromagnetically ordered down to 5 K. A transition to afm spin structure in a polycrystalline sample of the composition La2-2xSr1+2xMn2O7 has been observed for x = 0.25. La1.5Sr1.5Mn2O7 orders ferromagnetically at 66 K in a field of 0.5 T; the transition to an afm ordering occurs below TN = 34 K. In contrast to the Nd-substituted phase the afm transition only occurs for zero-field cooled measurements. At low temperature, T<TN, La1.5Sr1.5Mn2O7 undergoes a metamagnetic transition; the threshold field was found to depend strongly on the temperature (≈0.8 T at 20 K/≈3.5 T at 5 K). With the TMI of 102 K the compound shows metallic behaviour clearly above TC. It becomes insulating again at TN, which is in line with the properties of Nd0.2La1.2Sr1.6Mn2O7. Large magnetoresistance ratios (MR) have been measured for Nd0.2La1.8-2xSr1+2xMn2O7 with x = 0.4, 0.3 and La1.5Sr1.5Mn2O7 near TC. Furthermore, the metamagnetic transition causes high values of MR for La1.5Sr1.5Mn2O7 and Nd0.2La1.2Sr1.6Mn2O7 at low fields.

[1]  L. Schultz,et al.  Large magnetoresistance of the polycrystalline metamagnetic layered manganite La1.2Nd0.2Sr1.6Mn2O7 , 2000 .

[2]  Young-Uk Kwon,et al.  NEUTRON DIFFRACTION STUDIES ON A FERROMAGNETIC LAYERED MANGANITE LA2-2XSR1+2XMN2O7 (X=0.3) PREPARED BY A CERAMIC METHOD , 1999 .

[3]  S. Maekawa,et al.  Interrelation between orbital polarization and magnetic structure in bilayer manganites , 1999 .

[4]  L. Schultz,et al.  Magnetoresistance of polycrystalline layered manganites La2−2xSr1+2xMn2O7 , 1999 .

[5]  Y. Moritomo,et al.  CHEMICAL PRESSURE CONTROL OF THE SPIN-VALVE MAGNETORESISTANCE IN LA1.4SR1.6MN2O7 , 1999 .

[6]  J. Mitchell,et al.  Lattice effects and magnetic structure in the layered colossal magnetoresistance manganite La{sub 2-2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7}, x = 0.3. , 1999 .

[7]  Fangwei Wang,et al.  Chemically controlled properties of layered perovskites , 1999 .

[8]  Y. Moritomo,et al.  Layered Antiferromagnetic State in (Nd1-zLaz)Sr2Mn2O7. , 1999 .

[9]  Fangwei Wang,et al.  Magnetoresistance in layered perovskites La 1.2 - x Nd x Sr 1.8 Mn 2 O 7 , 1999 .

[10]  Ru‐Shi Liu,et al.  PRESSURE EFFECTS ON THE TRANSPORT AND MAGNETIC PROPERTIES OF LA1.4SR1.6MN2O7 , 1998 .

[11]  Y. Tokura,et al.  Ordered stack of spin valves in a layered magnetoresistive perovskite , 1998, cond-mat/9810382.

[12]  J. E. Millburn,et al.  Chemistry of naturally layered manganites (invited) , 1998 .

[13]  Young-Uk Kwon,et al.  Effect of lanthanide ions on the magnetotransport properties in layered Sr 1.6 R 1.4 Mn 2 O 7 ( R = L a , P r , N d , G d ) , 1998 .

[14]  Y. Moritomo,et al.  Layered-Type Antiferromagnetic State in Double-Layered Manganites: (La1-zNdz)2-2xSr1+2xMn2O7. , 1998 .

[15]  Y. Tomioka,et al.  Pressure-Enhanced Interplane Tunneling Magnetoresistance in a Layered Manganite Crystal , 1997 .

[16]  Y. Moritomo,et al.  Metal-insulator transition in layered manganites: (La{sub 1{minus}z}Nd{sub z}){sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} , 1997 .

[17]  J. Berthon,et al.  Ferromagnetism and thermoelectric power of La1.5Ca1.5Mn2O7 , 1997 .

[18]  J. E. Millburn,et al.  Antiferromagnetism, Ferromagnetism, and Phase Separation in the GMR System Sr2-xLa1+xMn2O7 , 1997 .

[19]  J. Goodenough,et al.  Sign Reversal of the Mn-O Bond Compressibility in La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} below {ital T}{sub {ital C}}: Exchange Striction in the Ferromagnetic State , 1997 .

[20]  J. Mitchell,et al.  Layered CMR manganites: Structure, properties, and unconventional magnetism , 1996 .

[21]  Y. Tomioka,et al.  Interplane Tunneling Magnetoresistance in a Layered Manganite Crystal , 1996, Science.

[22]  Sullivan,et al.  Crystal and magnetic structures of the colossal magnetoresistance manganates Sr2-xNd1+xMn2O7 (x=0.0, 0.1). , 1996, Physical review. B, Condensed matter.

[23]  A. Daoudi,et al.  Les solutions solides Sr3−xLnxMn2O7 (Ln = La, Nd, Sm, Gd) , 1984 .

[24]  X. Obradors,et al.  Semiconductor–metal transition, thermoelectric power and giant magneto resistance of the double Mn perovskite-La1.5Ca1.5Mn2O7 , 1999 .

[25]  Y. Moritomo,et al.  Competition of interbilayer magnetic couplings in R 1.4 Sr 1.6 Mn 2 O 7 ( R = La 1 − z Nd z ) , 1999 .