Spin glass-like phase below ∼210 K in magnetoelectric gallium ferrite

Mukherjee, Somdutta; Garg, Ashish; Gupta, Rajeev

doi:10.1063/1.3693400

Cited by 45 publications

(30 citation statements)

References 31 publications

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“…This strong f dependence indicates magnetic freezing behavior. The analysis can be made by the Vogel–Fulcher law that characterizes the time scale to overcome the energy barrier in the activation process for magnetically interacting particles,

1 / τ = 1 / τ_{0} e x p true[- E_{a} / k_{B} true(T_{f} - T_{0} true) true],

where E a is the activation energy and T 0 is the characteristic T associated with the inter‐cluster interaction energy . The fitted values from the plot in the inset of Figure b were attained as T 0 = 28.8 K and

E_{a} / k_{B}

= 87.8 K. The relatively large activation energy compared to the freezing T ,

E_{a} / k_{B}

= 2.8 T g , lies in the ordinary range for magnetic cluster‐glass materials …”

mentioning

confidence: 99%

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)

Moon

et al. 2019

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It has recently been reported that the exchange bias (EB) phenomenon in double-perovskite Y 2 CoMnO 6 ceramic arises from additional antiferromagnetic (AFM) clusters formed by the anti-sites of ionic disorders in the dominant ferromagnetic (FM) phase. To extensively examine the role of ionic orders and versatile magnetic interactions, we measure the magnetic properties of Y 2 Co 2 À x Mn x O 6 (x ¼ 1.0-1.9) compounds with different relative ratios of the magnetic ions. Upon increasing the ratio of Mn ions, the FM transition temperature is gradually lowered with a greatly enhanced EB effect for x ! 1.4. The measurement of heat capacity and AC magnetic susceptibility in the compound with x ¼ 1.5 suggests the formation of magnetic cluster-glass state from short-range FM order with comparable AFM clusters generated by the formation of Mn 3þ -O 2À -Mn 3þ bonds. The dependence of the EB effect on the cooling field reveals the maximum EB field at 2 K to be H EB ¼ 3.19 kOe. The large EB effect originates from the adjusted proportions of FM and AFM phases and the improved interfacial pinning of exchange coupling in the cluster-glass state. Our results, based on intricate magnetic correlations and phases, provide essential clues for exploring suitable ceramic compounds for magnetic functional applications.Magnetic devices having composite stacking geometry of different magnetic phases often display exchange bias (EB) effect, which is essential for manipulating magnetic hardness, such as attaining a pinned state of the read head for recording devices and a fixed reference layer for a spin valve as the basis of magnetic random-access memories. [1][2][3][4][5] The EB effect is associated with interfacial exchange interactions between ferromagnetic (FM) and antiferromagnetic (AFM) phases. [6][7][8][9][10] It occurs typically in thin film bilayers, reflected in the unidirectional anisotropy of the AFM layer coupled with interfacial magnetic moments of the FM layer upon cooling to the N eel temperature in an applied magnetic field. [11][12][13][14] Intensive studies of EB effect on core-shell nanostructures have been conducted to find efficient means for nanoscale miniaturization of magnetic devices. [8,[15][16][17][18] Many efforts have been made to realize the EB effect on bulk ceramic materials by taking advantage of a simple synthesis procedure. However, the bulk materials rarely reveal magnetic phase separation along with the desired magnetic anisotropy and hardness in each phase to demonstrate the EB effect. Many reports on bulk ceramics have stated that the EB effects originate from the formation of magnetic cluster-glass composed of interfaces between different magnetic states. [7,[19][20][21][22] Recently, double-perovskite R 2 CoMnO 6 (R ¼ La, . . ., Lu) compounds have been studied due to their fascinating functional properties like magnetocaloric effect, [23] exchange bias effect, [24] and multiferroicity, [25,26] arising from intricate magnetic phases and interactions. In these compounds, the incomplete exchange betw...

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1 / τ = 1 / τ_{0} e x p true[- E_{a} / k_{B} true(T_{f} - T_{0} true) true],

E_{a} / k_{B}

= 87.8 K. The relatively large activation energy compared to the freezing T ,

E_{a} / k_{B}

= 2.8 T g , lies in the ordinary range for magnetic cluster‐glass materials …”

mentioning

confidence: 99%

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)

Moon

et al. 2019

Physica Rapid Research Ltrs

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“…15 Though, the magnetic characteristics of GFO are widely studied, 10,13,[16][17][18] intriguingly there is no evidence of its ferroelectric nature. While an early report 19 attributed asymmetrically placed Ga1 ions within the unit cell responsible for observed piezoelectric response of GFO, recent first-principles calculations 20 showed that within the inherently distorted structure of GFO, large ionic displacements with respect to the centrosymmetric positions result in a large spontaneous polarization in the ground state 20 and even hint towards possible ferroelectric switching.…”

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confidence: 99%

Room Temperature Nanoscale Ferroelectricity in MagnetoelectricGaFeO3Epitaxial Thin Films

et al. 2013

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“…3(b). Here, we find that interestingly, the intrinsic bulk capacitance C B exhibits a peak at ∼ 300 K, close to the ferri-paramagnetic transition temperature (T C ) of GFO 17,26 which is indicative of magnetoelectric coupling in GFO.…”

Section: B Complex Electrical Modulus Analysismentioning

confidence: 86%

“…Consequently, such hopping of electrons may cause reorientation of the defect dipoles resulting in the observed Debye like relaxation. 22,24 Another notable feature of bulk relaxation is an abrupt change in the activation energy from 0.087±0.003 eV to 0.027±0.001 eV across 220 K, close to the observed spin-glass transition temperature (∼210 K) 26 in GFO. Although it is tempting to associate this change in activation energy across the spin-glass transition temperature (T s ) to possible correlation between spin waves (magnons) and dipole alignment, much lower magnon excitation energy (∼ 10 -3 eV) are found, in general, in magnetic oxides.…”

Section: B Complex Electrical Modulus Analysismentioning

confidence: 99%

Dielectric response and magnetoelectric coupling in single crystal gallium ferrite

2013

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Here we report the dielectric response and electric conduction behavior of magnetoelectric gallium ferrite single crystals studied using impedance analysis in time and temperature domain. The material exhibits two distinct relaxation processes: a high frequency bulk response and a low frequency interfacial boundary layer response. Calculated bulk capacitance as a function of temperature showed an anomaly at ferri- to paramagnetic transition temperature (∼ 300 K), suggestive of magneto-dielectric coupling in the material. Interestingly, we also witness an abrupt change in the activation energy at ∼ 220 K, in the vicinity of spin-glass transition temperature in GaFeO3

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Spin glass-like phase below ∼210 K in magnetoelectric gallium ferrite

Abstract: Coexistence of spin glass behavior and long-range ferrimagnetic ordering in La-and Dy-doped Co ferrite

Cited by 45 publications

References 31 publications

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)

Room Temperature Nanoscale Ferroelectricity in MagnetoelectricGaFeO3Epitaxial Thin Films

Dielectric response and magnetoelectric coupling in single crystal gallium ferrite

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Spin glass-like phase below ∼210 K in magnetoelectric gallium ferrite

Abstract: Coexistence of spin glass behavior and long-range ferrimagnetic ordering in La-and Dy-doped Co ferrite

Cited by 45 publications

References 31 publications

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y2Co2−xMnxO6 (x = 1.0–1.9)

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y2Co2−xMnxO6 (x = 1.0–1.9)

Room Temperature Nanoscale Ferroelectricity in MagnetoelectricGaFeO3Epitaxial Thin Films

Dielectric response and magnetoelectric coupling in single crystal gallium ferrite

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Product

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Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)

Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)