Memory and aging effects in NiO nanoparticles

Bisht, Vijay; Rajeev, K. P.

doi:10.1088/0953-8984/22/1/016003

Cited by 41 publications

(59 citation statements)

References 40 publications

(66 reference statements)

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“…In the subsequent heating run, we did not find any memory of the intermediate stops and this rules out the possibility of superparamagnetism or spin-glass behavior in the system. 44 We also carried out ZFC memory experiments on the system at 170 K and the result was negative. This confirms the conclusions we arrived at from the FC memory experiments and once again rules out a spin-glass state.…”

Section: Irreversibility (T Irr ) See Inset (I)mentioning

confidence: 99%

Spin-canted magnetism and decoupling of charge and spin ordering in NdNiO3

et al. 2013

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We report detailed magnetization measurements on the perovskite oxide NdNiO3. This system has a first order metal-insulator (M-I) transition at about 200 K which is associated with charge ordering. There is also a concurrent paramagnetic to antiferromagnetic spin ordering transition in the system. We show that the antiferromagnetic state of the nickel sublattice is spin canted. We also show that the concurrency of the charge ordering and spin ordering transitions is seen only while warming up the system from low temperature. The transitions are not concurrent while cooling the system through the M-I transition temperature. This is explained based on the fact that the charge ordering transition is first order while the spin ordering transition is continuous. In the magnetically ordered state the system exhibits ZFC-FC irreversibility, as well as history-dependent magnetization and aging. Our analysis rules out the possibility of spin-glass or superparamagnetism and suggests that the irreversibility arises from magnetocrystalline anisotropy and domain wall pinning.

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Section: Irreversibility (T Irr ) See Inset (I)mentioning

confidence: 99%

Spin-canted magnetism and decoupling of charge and spin ordering in NdNiO3

et al. 2013

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“…Generally these systems show non-equilibrium behavior at low temperature with features such as a bifurcation in field cooled (FC) and zero field cooled (ZFC) susceptibility, slow relaxation of magnetization, aging and memory effects. [2][3][4][5][6][7][8][9] It is widely believed that such non-equilibrium behavior exhibited by magnetic nanoparticles can arise mainly due to three mechanisms. First, in non interacting nanoparticle systems one can have superparamagnetism which arises from anisotropy energy barrier of each nanoparticle moment.…”

Section: Introductionmentioning

confidence: 99%

Anomalous magnetic behavior of CuO nanoparticles

Bisht

Rajeev

Banerjee

2010

Solid State Communications

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We report studies on temperature, field and time dependence of magnetization on cupric oxide nanoparticles of sizes 9 nm, 13 nm and 16 nm. The nanoparticles show unusual features in comparison to other antiferromagnetic nanoparticle systems. The field cooled (FC) and zero field cooled (ZFC) magnetization curves bifurcate well above the Néel temperature and the usual peak in the ZFC magnetization curve is absent. The system does not show any memory effects which is in sharp contrast to the usual behavior shown by other antiferromagnetic nanoparticles. It turns out that the non-equilibrium behavior of CuO nanoparticles is very strange and is neither superparamagnetic nor spin glass-like.

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“…Antiferromagnetic nanoparticles can also develop a net moment due to uncompensated spins and can exhibit superparamagnetism as proposed by Néel. 4,5 Thus magnetic nanoparticles are expected to show superparamagnetism, though, interparticle interactions can complicate matters leading to spin glass like behavior. [6][7][8][9][10][11] In addition to interparticle interactions, spin glass behavior can arise within a particle due to freezing of spins at the surface.…”

Section: -3mentioning

confidence: 99%

“…For example, NiO nanoparticles have been reported to show spin glass like behavior; 6,12 CuO nanoparticles show an anomalous magnetic behavior that cannot be described as superparamagnetic or spin glass like; 22 Ferritin shows superparamagnetic behavior 8,23 etc. Co 3 O 4 is an antiferromagnetic material and in the bulk form, its Néel temperature has been reported to lie between 30 K and 40 K. 24 There have been some reports on hysteresis, time dependence of magnetization, exchange bias and finite size effects in bare, coated and dispersed Co 3 O 4 nanoparticles and various claims have been made in support of spin glass like and superparamagnetic behavior in these particles.…”

Section: 19-21mentioning

confidence: 99%

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Non-equilibrium effects in the magnetic behavior of Co3O4 nanoparticles

Bisht

Rajeev

2011

Solid State Communications

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We report detailed studies on non-equilibrium magnetic behavior of antiferromagnetic Co3O4 nanoparticles. Temperature and field dependence of magnetization, wait time dependence of magnetic relaxation (aging), memory effects and temperature dependence of specific heat have been investigated to understand the magnetic behavior of these particles. We find that the system shows some features characteristic of nanoparticle magnetism such as bifurcation of field cooled (FC) and zero field cooled (ZFC) susceptibilities and a slow relaxation of magnetization. However, strangely, the temperature at which the ZFC magnetization peaks coincides with the bifurcation temperature and does not shift on application of magnetic fields up to 1 kOe, unlike most other nanoparticle systems. Aging effects in these particles are negligible in both FC and ZFC protocol and memory effects are present only in FC protocol. We estimate the Néel temperature by using Fisher's relation as well as directly by measurement of specific heat, thus testing the validity of Fisher's relation for nanoparticles. We show that Co3O4 nanoparticles constitute a unique aniferromagnetic system which develops a magnetic moment in the paramagnetic state because of antiferromagnetic correlations and enters into a blocked state above the Néel temperature.

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Memory and aging effects in NiO nanoparticles

Cited by 41 publications

References 40 publications

Spin-canted magnetism and decoupling of charge and spin ordering in NdNiO3

Spin-canted magnetism and decoupling of charge and spin ordering in NdNiO3

Anomalous magnetic behavior of CuO nanoparticles

Non-equilibrium effects in the magnetic behavior of Co3O4 nanoparticles

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