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Gopalakrishnan, J.; Peng, J. L.; Li, Qi; Xiong, Ge; Venkatesan, T.; Greene, R. L.

doi:10.1103/physrevb.51.6143

Cited by 551 publications

(227 citation statements)

References 16 publications

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“…Ag composites Ag is not substituted into main LCMO lattice but remain rather as an additive in the system. (280 K) is comparable to aligned thin films [6,8,15] of LCMO, and to our knowledge is the best one yet obtained for any polycrystalline mangenites. As far fixed temperature and varying field MR is concerned its shape is changed from U type to V type.…”

mentioning

confidence: 54%

“…In case of Ag = 0.2, 0.3 and 0.4 samples the transition is quite sharp and the obvious LCMO polycrystalline hump is not seen, further TCR is improved by nearly an order of magnitude. To our knowledge these are first LCMO:Ag polycrystalline compounds having very sharp T MI , which is generally the case for aligned LCMO films [6,8,15] or single crystals [9]. For large applications occasionally the bulk compounds in form of solid rods etc are required and hence the present LCMO:Ag composites will prove to be very useful in this direction.…”

Section: Introductionmentioning

confidence: 99%

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Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Awana

Tripathi

Balamurugan

et al. 2006

Solid State Communications

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We report the synthesis, (micro)structural, magneto-transport and magnetization of polycrystalline La 2/3 Ca 1/3 MnO 3 :Ag x composites with x = 0.0, 0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition is increased significantly with addition of Ag. The FM transition temperature (T FM ) is also increased slightly with Ag addition. Magneto-transport measurements revealed that magneto-resistance MR is found to be maximum near T FM . Further the increased MR of up to 60% is seen above 300 K for higher silver added samples in an applied field of 7 Tesla. Sharp TCR is seen near T FM with highest value of up to 15 % for Ag (0.4) sample, which is an order of magnitude higher than as for present pristine sample and best value yet reported for any polycrystalline LCMO compound. Increased TCR, T FM and significant above room temperature MR of La 2/3 Ca 1/3 MnO 3 :Ag x composites is explained on the basis of improved grains size and connectivity with silver addition in the matrix. Better coupled FM domains and nearly conducting grain boundaries give rise to improved physical properties of the La 2/3 Ca 1/3 MnO 3 manganites. Ag composites Ag is not substituted into main LCMO lattice but remain rather as an additive in the system. (280 K) is comparable to aligned thin films [6,8,15] of LCMO, and to our knowledge is the best one yet obtained for any polycrystalline mangenites. As far fixed temperature and varying field MR is concerned its shape is changed from U type to V type. And is maximum at all fields up to 7 Tesla at 300 K. Infact with an increase in Ag content the low T below 300K MR% decrease and the room temperature 300 K increase. For LCMO: Ag (0.4) sample the MR of up to 60% is observed in 7 Tesla field at 300 K. Even at low fields of say 1 Tesla the MR of up to 16% is seen.The results of magnetization and magneto transport of LCMO:Ag x composites can be summarized as follows: 7 1. Ag does not substitute into host LCMO matrix in our polycrystalline LCMO:Ag x composites but improved significantly the grain morphology of the host.2. The T MI and T c remain nearly invariant with increase in x (Ag content).3. The sharpness of insulator-metal transition increases dramatically with increase in x (Ag content) and high (15%) sharp TCR is observed for Ag composites 4. Though the MR is seen in all the samples right from 300 K down to 5 K, the same is negligible at 300 K and more at lower T for pure sample and is maximum at 300 K and least at 5 K for Ag (0.4) containing compounds. DISCUSSIONNow we try to explain in broad sense the main results summarized above, as far as (1) is concerned there are some very recent reports in literature, which deals with the LCMO and LCMO/ZrO 2 [20]. In all these composites the quality of the LCMO was deteriorated. In case of LCMO:Ag there is a good probability of Ag being distributed at grain boundaries and hence providing better connectivity of grains, which is seen in Fig. 2(b). In most of other composites [16][17][18][19][20] the addi...

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mentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Awana

Tripathi

Balamurugan

et al. 2006

Solid State Communications

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“…The large magnetic-entropy change in perovskite manganites is believed to be originated from the role played by spin-lattice coupling in the magnetic ordering process [32]. A significant change accompanying the magnetic transition due to strong coupling between spin and lattice in perovskite manganites has been observed [33] resulting in lattice structure changes e.g.…”

Section: Magnetocaloric Effectmentioning

confidence: 99%

Magnetic and Magnetocaloric Properties of La0.67Pb0.33−x Ag x MnO3 Compounds

Mtiraoui

Dhahri

Oumezine

et al. 2012

J Supercond Nov Magn

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In this paper, we have studied the magnetic and magnetocaloric properties of the perovskite manganites La 0.67 Pb 0.33−x Ag x MnO 3 (0 ≤ x ≤ 0.15), which show a sharp paramagnetic-ferromagnetic phase transition over a wide temperature range (T = 250-401 K). The Curie temperature has been analyzed by two methods: using the numerical derivative dM/dT and the thermodynamic model. The experimental results indicate that T C decreases from 368 to 288 K with increasing Ag substitution independently of the method used to obtain T C . Upon 10 KOe applied magnetic field, the large magnetic-entropy change (| S M |) reaches values of 2.75, 3, 3.25 and 3.5 J/kg K for x = 0, 0.05, 0.10 and 0.15 compositions, respectively, which are comparable to that of Gd. The relative cooling power (RCP) increases with increasing Ag content from 68.75 (x = 0) to 156.27 J/kg (x = 0.15) for H = 10 KOe. Through these results, La 0.67 Pb 0.33−x Ag x MnO 3 materials are strongly suggested for the use of active refrigerants for magnetic refrigeration technology near room temperature.N. Mtiraoui ( ) · M. Oumezine

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“…The first approach is to use a crystalline grain-boundary as the interface, and study the spin-dependent transport across. The role of grain boundary in providing additional contributions to low-field magnetoresistance has long been suspected (Ju et al, 1995;Gupta et al, 1996;Hwang et al, 1996). Direct experimental observation of grain-boundary-originated magnetoresistance has recently been made (Mathur et al, 1997;Steenbeck et al, 1997) which shows a 30% magnetoresistance in a field of less than 500 Oe.…”

Section: Introductionmentioning

confidence: 99%

Thin–film trilayer manganate junctions

1998

Philosophical Transactions of the Royal Society of London. Seri

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Spin-dependent conductance across a manganate-barrier-manganate junction has recently been demonstrated. The junction is a La 0.67 Sr 0.33 MnO 3 -SrTiO 3 -La 0.67 Sr 0.33 MnO 3 trilayer device supporting current-perpendicular transport. Large magnetoresistance of up to a factor of five change was observed in these junctions at 4.2K in a relatively low field of the order of 100 Oe. Temperature and bias dependent studies revealed a complex junction interface structure whose materials physics has yet to be understood.

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Dependence of giant magnetoresistance on oxygen stoichiometry and magnetization in polycrystallineLa0.67Ba0.33

Cited by 551 publications

References 16 publications

Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Magneto-transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3 : Ag polycrystalline composites

Magnetic and Magnetocaloric Properties of La0.67Pb0.33−x Ag x MnO3 Compounds

Thin–film trilayer manganate junctions

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