Magnanite multilayers have been fabricated using La 0.67 Ca 0.33 MnO 3 as the ferromagnetic layer... more Magnanite multilayers have been fabricated using La 0.67 Ca 0.33 MnO 3 as the ferromagnetic layer and Pr 0.7 Ca 0.3 MnO 3 and Nd 0.5 Ca 0.5 MnO 3 as the spacer layers. All the multilayers were grown on LaAlO 3 (100) by pulse laser deposition. An enhanced magnetoresistnace (defined (R H -R 0 )/R 0 ) of more than 98% is observed in these multilayers. Also a low field magnetoresistance of 41% at 5000 Oe is observed in these multilayer films. The enhanced MR is attributed to the induced double exchange in the spacer layer, which is giving rise to more number of conducting carriers. This is compared by replacing the spacer layer with LaMnO 3 where Mn exists only in 3+ state and no enhancement is observed in the La 0.67 Ca 0.33 MnO 3 / LaMnO 3 multilayers as double exchange mechanism can not be induced by external magnetic fields.
We present a magnetic study of the insulating perovskite LaMn 1Àx Ti x O 3+d (0oxp0.2) including ... more We present a magnetic study of the insulating perovskite LaMn 1Àx Ti x O 3+d (0oxp0.2) including measurements of magnetization, susceptibility, and magnetic relaxation. The Curie temperature was found to decrease with increasing content of Ti. Two distinct magnetic transitions, irreversibility, non-exponential relaxation and aging effects confirm a reentrant spin-glass state for x=0.2. The time decay of the magnetization has an algebraic functional form for times up to 2 h. The specific heat also displays characteristic features of a spin-glass system by a linear low-temperature dependence and a broadened peak near the temperature of the reentrant transition. r
Electrical transport properties of RNiO 3 (R Pr, Nd, Sm) thin ®lms grown by pulsed laser depositi... more Electrical transport properties of RNiO 3 (R Pr, Nd, Sm) thin ®lms grown by pulsed laser deposition have been studied. RNiO 3 ®lms grow in the (1 0 0) direction on a LaAlO 3 (1 0 0) substrate. Unlike the polycrystalline solid, PrNiO 3 ®lms showed metallic behavior. The ®rstorder metal-to-insulator transition observed in polycrystalline solids is suppressed in RNiO 3 ®lms. The effect of lattice strain in the ®lms in¯uencing the transport properties has been studied by varying the thickness of PrNiO 3 ®lm on LaAlO 3 (1 0 0) and also by growing them on SrTiO 3 (1 0 0) and a-Al 2 O 3 (1 1 0 2) substrates. Deviation in the transport properties is explained due to the strain-induced growth of the ®lms. Further, we show that the transport property of a LaNiO 3 ®lm is also in¯uenced by a similar strain effect. #
The magnetic and transport behavior of the multilayers of ferromagnetic (La 0.6 Pb 0.4 MnO 3 )/no... more The magnetic and transport behavior of the multilayers of ferromagnetic (La 0.6 Pb 0.4 MnO 3 )/nonmagnetic metallic oxide (La 4 BaCu 5 O 13+x ) fabricated on LaAlO 3 (100) substrate by pulsed laser deposition has been investigated. The thickness of the nonmagnetic layer ...
Epitaxial films of Sr 2 FeMoO 6 were grown on SrTiO 3 (100) substrates by pulsed laser deposition... more Epitaxial films of Sr 2 FeMoO 6 were grown on SrTiO 3 (100) substrates by pulsed laser deposition; optimised growth conditions give a saturation magnetization of 4.0m B implying a high degree of B-site ordering. The films show very high crystallinity and smooth surfaces. We have compared the B-site disorder in the films with saturation magnetization and show that the rate of suppression with disorder is lower than that suggested by Monte Carlo simulations, suggesting the ferromagnetic coupling in the Fe/Mo sublattices. q
We have grown Bi 2 Sr 2 Co 2 O y thin films on LaAlO 3 ͑100͒ and fused silica substrates by pulse... more We have grown Bi 2 Sr 2 Co 2 O y thin films on LaAlO 3 ͑100͒ and fused silica substrates by pulsed laser deposition. The films on LaAlO 3 are c-axis oriented and partially in-plane aligned with multiple domains, while the films on fused silica are preferred c-axis oriented without in-plane alignment. The Seebeck coefficient and resistivity of films on both substrates are comparable to those of single crystals. An oxide p-n heterojunction was formed by depositing Bi 2 Sr 2 Co 2 O y film on Nb-doped SrTiO 3 single crystal, which showed a rectifying behavior. These thin films and heterostructures may be used for future thermoelectric applications.
Thin films of Pr 0.7 Ca 0.3 MnO 3 , Nd 0.5 Ca 0.5 MnO 3 and Nd 0.5 Sr 0.5 MnO 3 have been fabrica... more Thin films of Pr 0.7 Ca 0.3 MnO 3 , Nd 0.5 Ca 0.5 MnO 3 and Nd 0.5 Sr 0.5 MnO 3 have been fabricated . by pulse laser deposition. Magnetic and electrical transport properties of these films were compared with their bulk solids. All the films grow in (101) direction on LaAlO 3 (100).
We report on transient reflectivity and magneto-optical Kerr measurements from the colossal magne... more We report on transient reflectivity and magneto-optical Kerr measurements from the colossal magnetoresistance compounds La 0.67 Ca 0.33 MnO 3 (LCMO), La 0.67 Sr 0.33 MnO 3 (LSMO), and Sr 2 FeMoO 6 (SFMO) as a function of temperature and magnetic field. In ...
We have synthesized Bi 3 Fe 4 Ga 1 O 12 (BIGG) films on Gd 3 Ga 5 O 12 and Gd 3 (ScGa) 5 O 12 sub... more We have synthesized Bi 3 Fe 4 Ga 1 O 12 (BIGG) films on Gd 3 Ga 5 O 12 and Gd 3 (ScGa) 5 O 12 substrates by a pulsed laser deposition technique. X-ray diffraction and rocking curve analyses confirm the epitaxial quality of the films with a lattice constant close to 12 61 0 01 A. Compared with that of a bismuth iron garnet Bi 3 Fe 5 O 12 (BIG) film, the bandwidth of the BIGG transmittance (T) spectrum is extended and its left edge shifted down in wavelength by approximately 50 nm. This enables its Faraday rotation F and switching speed to be tested at a wavelength of 532 nm. While BIGG film has a Faraday rotation angle slightly less than that of BIG film, its magnetooptical figure of merit, 2 F d -ln(T%), is greatly improved to a typical value 1 8 times larger than that of the BIG film. Further, the high-speed pulse response time of the BIGG film reaches 2.4 ns with a 1 mm aperture size at the wavelength of 532 nm.
The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistanc... more The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistance compound La0.67Sr0.33MnO3 LSMO using ultrafast time-resolved optical techniques. Two-color pump-probe setup was employed to record the photoinduced reflectance oscillations due ...
The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistanc... more The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistance compound La0.67Sr0.33MnO3 LSMO using ultrafast time-resolved optical techniques. Two-color pump-probe setup was employed to record the photoinduced reflectance oscillations due ...
Epitaxial and c-axis preferred oriented oxide thermoelectric Bi$_{2}$Sr$_{2}$Co$_{2}$O$_{y }$ thi... more Epitaxial and c-axis preferred oriented oxide thermoelectric Bi$_{2}$Sr$_{2}$Co$_{2}$O$_{y }$ thin films have been deposited on LaAlO$_{3}$ (100), Al$_{2}$O$_{3 }$(0001) and fused silica substrates using pulsed laser deposition. At room temperature, the Seebeck ...
We investigated the magnetic anisotropic parameters and spin-wave relaxation of thin films of the... more We investigated the magnetic anisotropic parameters and spin-wave relaxation of thin films of the ferromagnetic half-metallic by ferromagnetic resonance technique. The resonance field and linewidth were recorded as a function of relative angle between applied magnetic field ...
The ferroelectric polymer PVDF (Polyvinyledene fluoride) and nano crystalline nickel composites w... more The ferroelectric polymer PVDF (Polyvinyledene fluoride) and nano crystalline nickel composites were prepared through simple tape casting technique. The structural, electrical and magnetic properties of the as prepared samples were carried out at room temperature. The ferroelectric and ferromagnetic behaviors of the composites have undergone modifications with the increase of concentration of nickel in the composites.
We report on time-resolved ultrafast optical measurements on a La$_{1-x}$Ca$_{x}$MnO$_{ 3}$ (LCMO... more We report on time-resolved ultrafast optical measurements on a La$_{1-x}$Ca$_{x}$MnO$_{ 3}$ (LCMO) single crystal ($x $= 0.3) and thin film ($x$= 0.33). The differential reflectivity shows coherent GHz oscillations due to the excitation of longitudinal acoustic (LA) phonons. The ...
Magnanite multilayers have been fabricated using La 0.67 Ca 0.33 MnO 3 as the ferromagnetic layer... more Magnanite multilayers have been fabricated using La 0.67 Ca 0.33 MnO 3 as the ferromagnetic layer and Pr 0.7 Ca 0.3 MnO 3 and Nd 0.5 Ca 0.5 MnO 3 as the spacer layers. All the multilayers were grown on LaAlO 3 (100) by pulse laser deposition. An enhanced magnetoresistnace (defined (R H -R 0 )/R 0 ) of more than 98% is observed in these multilayers. Also a low field magnetoresistance of 41% at 5000 Oe is observed in these multilayer films. The enhanced MR is attributed to the induced double exchange in the spacer layer, which is giving rise to more number of conducting carriers. This is compared by replacing the spacer layer with LaMnO 3 where Mn exists only in 3+ state and no enhancement is observed in the La 0.67 Ca 0.33 MnO 3 / LaMnO 3 multilayers as double exchange mechanism can not be induced by external magnetic fields.
We present a magnetic study of the insulating perovskite LaMn 1Àx Ti x O 3+d (0oxp0.2) including ... more We present a magnetic study of the insulating perovskite LaMn 1Àx Ti x O 3+d (0oxp0.2) including measurements of magnetization, susceptibility, and magnetic relaxation. The Curie temperature was found to decrease with increasing content of Ti. Two distinct magnetic transitions, irreversibility, non-exponential relaxation and aging effects confirm a reentrant spin-glass state for x=0.2. The time decay of the magnetization has an algebraic functional form for times up to 2 h. The specific heat also displays characteristic features of a spin-glass system by a linear low-temperature dependence and a broadened peak near the temperature of the reentrant transition. r
Electrical transport properties of RNiO 3 (R Pr, Nd, Sm) thin ®lms grown by pulsed laser depositi... more Electrical transport properties of RNiO 3 (R Pr, Nd, Sm) thin ®lms grown by pulsed laser deposition have been studied. RNiO 3 ®lms grow in the (1 0 0) direction on a LaAlO 3 (1 0 0) substrate. Unlike the polycrystalline solid, PrNiO 3 ®lms showed metallic behavior. The ®rstorder metal-to-insulator transition observed in polycrystalline solids is suppressed in RNiO 3 ®lms. The effect of lattice strain in the ®lms in¯uencing the transport properties has been studied by varying the thickness of PrNiO 3 ®lm on LaAlO 3 (1 0 0) and also by growing them on SrTiO 3 (1 0 0) and a-Al 2 O 3 (1 1 0 2) substrates. Deviation in the transport properties is explained due to the strain-induced growth of the ®lms. Further, we show that the transport property of a LaNiO 3 ®lm is also in¯uenced by a similar strain effect. #
The magnetic and transport behavior of the multilayers of ferromagnetic (La 0.6 Pb 0.4 MnO 3 )/no... more The magnetic and transport behavior of the multilayers of ferromagnetic (La 0.6 Pb 0.4 MnO 3 )/nonmagnetic metallic oxide (La 4 BaCu 5 O 13+x ) fabricated on LaAlO 3 (100) substrate by pulsed laser deposition has been investigated. The thickness of the nonmagnetic layer ...
Epitaxial films of Sr 2 FeMoO 6 were grown on SrTiO 3 (100) substrates by pulsed laser deposition... more Epitaxial films of Sr 2 FeMoO 6 were grown on SrTiO 3 (100) substrates by pulsed laser deposition; optimised growth conditions give a saturation magnetization of 4.0m B implying a high degree of B-site ordering. The films show very high crystallinity and smooth surfaces. We have compared the B-site disorder in the films with saturation magnetization and show that the rate of suppression with disorder is lower than that suggested by Monte Carlo simulations, suggesting the ferromagnetic coupling in the Fe/Mo sublattices. q
We have grown Bi 2 Sr 2 Co 2 O y thin films on LaAlO 3 ͑100͒ and fused silica substrates by pulse... more We have grown Bi 2 Sr 2 Co 2 O y thin films on LaAlO 3 ͑100͒ and fused silica substrates by pulsed laser deposition. The films on LaAlO 3 are c-axis oriented and partially in-plane aligned with multiple domains, while the films on fused silica are preferred c-axis oriented without in-plane alignment. The Seebeck coefficient and resistivity of films on both substrates are comparable to those of single crystals. An oxide p-n heterojunction was formed by depositing Bi 2 Sr 2 Co 2 O y film on Nb-doped SrTiO 3 single crystal, which showed a rectifying behavior. These thin films and heterostructures may be used for future thermoelectric applications.
Thin films of Pr 0.7 Ca 0.3 MnO 3 , Nd 0.5 Ca 0.5 MnO 3 and Nd 0.5 Sr 0.5 MnO 3 have been fabrica... more Thin films of Pr 0.7 Ca 0.3 MnO 3 , Nd 0.5 Ca 0.5 MnO 3 and Nd 0.5 Sr 0.5 MnO 3 have been fabricated . by pulse laser deposition. Magnetic and electrical transport properties of these films were compared with their bulk solids. All the films grow in (101) direction on LaAlO 3 (100).
We report on transient reflectivity and magneto-optical Kerr measurements from the colossal magne... more We report on transient reflectivity and magneto-optical Kerr measurements from the colossal magnetoresistance compounds La 0.67 Ca 0.33 MnO 3 (LCMO), La 0.67 Sr 0.33 MnO 3 (LSMO), and Sr 2 FeMoO 6 (SFMO) as a function of temperature and magnetic field. In ...
We have synthesized Bi 3 Fe 4 Ga 1 O 12 (BIGG) films on Gd 3 Ga 5 O 12 and Gd 3 (ScGa) 5 O 12 sub... more We have synthesized Bi 3 Fe 4 Ga 1 O 12 (BIGG) films on Gd 3 Ga 5 O 12 and Gd 3 (ScGa) 5 O 12 substrates by a pulsed laser deposition technique. X-ray diffraction and rocking curve analyses confirm the epitaxial quality of the films with a lattice constant close to 12 61 0 01 A. Compared with that of a bismuth iron garnet Bi 3 Fe 5 O 12 (BIG) film, the bandwidth of the BIGG transmittance (T) spectrum is extended and its left edge shifted down in wavelength by approximately 50 nm. This enables its Faraday rotation F and switching speed to be tested at a wavelength of 532 nm. While BIGG film has a Faraday rotation angle slightly less than that of BIG film, its magnetooptical figure of merit, 2 F d -ln(T%), is greatly improved to a typical value 1 8 times larger than that of the BIG film. Further, the high-speed pulse response time of the BIGG film reaches 2.4 ns with a 1 mm aperture size at the wavelength of 532 nm.
The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistanc... more The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistance compound La0.67Sr0.33MnO3 LSMO using ultrafast time-resolved optical techniques. Two-color pump-probe setup was employed to record the photoinduced reflectance oscillations due ...
The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistanc... more The authors report on an anomalous first-to-zero sound crossover in the colossal magnetoresistance compound La0.67Sr0.33MnO3 LSMO using ultrafast time-resolved optical techniques. Two-color pump-probe setup was employed to record the photoinduced reflectance oscillations due ...
Epitaxial and c-axis preferred oriented oxide thermoelectric Bi$_{2}$Sr$_{2}$Co$_{2}$O$_{y }$ thi... more Epitaxial and c-axis preferred oriented oxide thermoelectric Bi$_{2}$Sr$_{2}$Co$_{2}$O$_{y }$ thin films have been deposited on LaAlO$_{3}$ (100), Al$_{2}$O$_{3 }$(0001) and fused silica substrates using pulsed laser deposition. At room temperature, the Seebeck ...
We investigated the magnetic anisotropic parameters and spin-wave relaxation of thin films of the... more We investigated the magnetic anisotropic parameters and spin-wave relaxation of thin films of the ferromagnetic half-metallic by ferromagnetic resonance technique. The resonance field and linewidth were recorded as a function of relative angle between applied magnetic field ...
The ferroelectric polymer PVDF (Polyvinyledene fluoride) and nano crystalline nickel composites w... more The ferroelectric polymer PVDF (Polyvinyledene fluoride) and nano crystalline nickel composites were prepared through simple tape casting technique. The structural, electrical and magnetic properties of the as prepared samples were carried out at room temperature. The ferroelectric and ferromagnetic behaviors of the composites have undergone modifications with the increase of concentration of nickel in the composites.
We report on time-resolved ultrafast optical measurements on a La$_{1-x}$Ca$_{x}$MnO$_{ 3}$ (LCMO... more We report on time-resolved ultrafast optical measurements on a La$_{1-x}$Ca$_{x}$MnO$_{ 3}$ (LCMO) single crystal ($x $= 0.3) and thin film ($x$= 0.33). The differential reflectivity shows coherent GHz oscillations due to the excitation of longitudinal acoustic (LA) phonons. The ...
Uploads
Papers by Adyam V