The effect of artificial boundary grain on the magneto- and electro-transport properties of (1 − x)La0.7Ca0.3MnO3 + xA (A = Al2O3 and Ag) nanocomposite

Tóm tắt

The magneto- and electro-transport properties of two series of nanocrystalline (1 − x)La0.7Ca0.3MnO3 + xA (A: Al2O3 and Ag) composites have been systematically and thoroughly studied. The observed electronic transport behavior over the whole temperature range (5–300 K), especially the change in metal–insulator transition temperature with increasing Al2O3 and Ag content while the ferromagnetic–paramagnetic transition remained unaffected, was explained by applying a two-component phenomenological model. We have attributed the unusual low-temperature resistivity upturn of composites to a change in charging energy. Most interestingly, magneto-transport measurements showed that the low-field magnetoresistance (LFMR), as well as the high-field magnetoresistance (HFMR), displayed a Curie–Weiss-like law behavior. Basing on the spin-polarized transport of conduction electrons at the grain boundaries, we have analyzed our experimental data and found that the temperature dependence of low- and high-field magnetoresistance is controlled predominantly by the nature of the temperature response of surface magnetization of particles. The competition between grain-boundary pinning strength (k), magnetic field and thermal energy (kBT ) created the temperature sensitive behavior of magnetoresistance as well as that of surface spin susceptibility (χb).

Từ khoá

Keywords: manganite composites, low-field magnetoresistance, polarized tunneling

Tài liệu tham khảo

[1] Zener C 1951 Phys. Rev. 82 403

[2] Hwang H Y, Cheong S W, Ong N P and Batlogg B 1996 Phys. Rev. Lett. 77 2041

[3] Gupta A and Sun J S 1999 J. Magn. Magn. Mater. 200 24

[4] Sandu V, Popa S, Ivan I, Plapcianu C, Sandu E, Hurduc N and Nor I 2009 Proc. SPIE 7493 74934F-1

[5] Balcells L, Fontcuberta J, Martínez B and Obradors X 1998 J. Phys.: Condens. Matter. 10 1883

[6] Gaur A and Varma G D 2008 J. Alloys Compd. 453 423

[7] Phong P T, Khiem N V, Dai N V, Manh D H, Hong L V and Phuc N X 2009 Mater. Lett. 63 353

[8] Kumar J, Singh R K, Singh H K, Siwach P K, Ramadhar Singh and Srivastava O N 2008 J. Alloys Compd. 455 289

[9] Miao J H, Yuan S L, Yuan L, Ren G M, Xiao X, Yu G Q, Wang Y Q and Yin S Y 2008 Mater. Res. Bull. 43 631

[10] Eshraghi M, Salamati H and Kameli P 2007 J. Alloys Compd. 437 22

[11] Hong C S, Kim W S and Hur N H 2002 Solid State Commun. 121 657 [12] Gaur A and Varma G D 2006 Solid State Commun. 139 310

[13] Khiem N V, Phong P T, Dai N V, Manh D H, Hong L V and Phuc N X 2009 Mater. Lett. 63 899

[14] Awana V P S, Tripathi R, Balamurugan S, Kishan H and Takayama-Muromachi E 2006 Solid State Commun. 140 410

[15] Phong P T, Khiem N V, Dai N V, Manh D H, Hong L V and Phuc N X 2009 J. Alloys Compd. 484 12

[16] Xiong C, Hu H, Xiong Y, Zhang Z, Pi H, Wu X, Li L, Wei F and Zheng C 2009 J. Alloys Compd. 479 357

[17] Phong P T, Dai N V, Manh D H, Khiem N V, Hong L V and Phuc N X 2009 J. Alloys Compd. 485 L39

[18] Phong P T, Khiem N V, Dai N V, Manh D H, Hong L V and Phuc N X 2009 J. Magn. Magn. Mater. 321 3330

[19] Thanh T D, Phong P T, Dai N V, Manh D H, Khiem N V, Hong L V and Phuc N X 2011 J. Magn. Magn. Mater. 323 179

[20] Lee S, Hwang H Y, Shraiman B I, Ratcliff W D II and Cheong S-W 1999 Phys. Rev. Lett. 82 4508

[21] de Andres, Garcia-Hernandez M and Martinez J L 1999 Phys. Rev. B 60 7328 8 Adv. Nat. Sci.: Nanosci. Nanotechnol. 2 (2011) 025003 T P Pham et al

[22] Rubinstein J M 2000 J. Appl. Phys. 87 5019

[23] Das D, Srivastava, Bahadur D, Nigam A K and Malik S K 2004 J. Phys.: Condens. Matter 16 4089

[24] Li J, Huang Q, Li Z W, You L P, Xu S Y and Ong C K 2001 J. Appl. Phys. 89 7428

[25] Sheng P, Abeles B and Arie Y 1973 Phys. Rev. B 31 44

[26] Raychaudhuri P, Sheshadri K, Taneja P, Bandyopadhyay S, Ayyub P, Nigam A K and Pinto R 1998 J. Appl. Phys. 84 2048

[27] Dey P and Nath T K 2006 Phys. Rev. B 73 214425