Signatures of spin-phonon coupling in hematite crystallites through dielectric and Raman spectroscopy

Pattanayak, Namrata; Kumar, Jitender; Patra, Partha; Kumar, G. V. Pavan; Bajpai, Abhishek

doi:10.1209/0295-5075/134/47003

Cited by 7 publications

(4 citation statements)

References 44 publications

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“…The three peaks located at 214, 306, and 368 cm –1 for FeS@NCG correspond to the E g , A g , and E g modes of FeS, respectively . The peaks between 185 and 791 cm –1 belong to the Fe 2 O 3 crystal . Meanwhile, two strong broad peaks, located at 1340 and 1592 cm –l , are assigned to the D- and G-band peaks, respectively, for graphene oxide .…”

Section: Resultsmentioning

confidence: 96%

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes

Yang

Yadav

Jeon

et al. 2022

ACS Appl. Mater. Interfaces

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The development of advanced hierarchical anode materials has recently become essential to achieving high-performance sodium-ion batteries. Herein, we developed a facile and cost-effective scheme for synthesizing graphene-wrapped, nitrogen-rich carbon-coated iron sulfide nanofibers (FeS@NCG) as an anode for SIBs. The designed FeS@NCG can provide a significant reversible capacity of 748.5 mAh g–1 at 0.3 A g–1 for 50 cycles and approximately 3.9-fold higher electrochemical performance than its oxide analog (Fe2O3@NCG, 192.7 mAh g–1 at 0.3 A g–1 for 50 cycles). The sulfur- and nitrogen-rich multilayer package structure facilitates efficient suppression of the porous FeS volume expansion during the sodiation process, enabling a long cycle life. The intimate contact between graphene and porous carbon-coated FeS nanofibers offers strong structural barriers associated with charge-transfer pathways during sodium insertion/extraction. It also reduces the dissolution of polysulfides, enabling efficient sodium storage with superior stable kinetics. Furthermore, outstanding capacity retention of 535 mAh g–1 at 5 A g–1 is achieved over 1010 cycles. The FeS@NCG also exhibited a specific capacity of 640 mAh g–1 with a Coulombic efficiency of above 99.8% at 5 A g–1 at 80 °C, indicating its development prospects in high-performance SIB applications.

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Section: Resultsmentioning

confidence: 96%

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes

Yang

Yadav

Jeon

et al. 2022

ACS Appl. Mater. Interfaces

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“…Raman Shift (cm −1 ) Modes Raman Shift (cm −1 ) A1g( 1 In the following, the evolution of the Raman modes with temperature is studied from 80 to 600 K, both during the heating (Figure 4a) and cooling process (Figure 4b), examining possible hysteretic effects when the material passes through the Morin transition. Likewise, a Lorentzian fit is performed to obtain the position of vibrational modes and their evolution with temperature being adjusted according to anharmonic and Lorentzian fittings to identify trends (Figure 5) [64][65][66]. In general, large effects are observed in all modes due to lattice compression and phonon-phonon interactions as the temperature decreases (cooling curve in Figure 4b).…”

Section: Modesmentioning

confidence: 99%

Large Two-Magnon Raman Hysteresis Observed in a Magnetically Uncompensated Hematite Coating across the Morin Transition

et al. 2022

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A temperature-dependent Raman experiment between 80 and 600 K was performed in a nanoparticulated coating of single-phase hematite grown on a silica substrate. In that range, a thermal Raman shift hysteresis was identified in the vibrational modes that accompanies the Morin transition, observing large effects in the two-magnon Raman frequency position and in its relative intensity. Interestingly, no decrease in coercivity occurs when the hematite crosses the Morin transition below 230 K. The spin-flop processes produced in the coating leads to a strong decompensation of the surface spins, generating a ferromagnetic component over the whole temperature range studied. Such unusual effects might be promoted by a certain degree of structural disorder and the stresses produced by the nanoparticulation growth approach of the hematite coating. As a result, a high stability of the two-magnon excitation is obtained over a wide temperature range and considerable advances are made for the development of spintronic devices based on semiconductor antiferromagnetic materials.

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“…To characterize the coupling between the phonon and spin excitation, a common method is to use the phonon-magnon coupling or magnetoelastic coupling [21][22][23][24][25][26][27][28]. Pattanayak et al [29] recently detected some of the key signatures of spin-phonon coupling in hematite crystallites through dielectric and Raman spectroscopy. However, a single spin-phonon coupling constant is hardly enough to capture the complexity as how spin and phonon interact with each other.…”

Section: Introductionmentioning

confidence: 99%

Spin–phonon dispersion in magnetic materials

Bai

Zhang

et al. 2022

J. Phys.: Condens. Matter

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Microscopic coupling between the electron spin and the lattice vibration is responsible for an array of exotic properties from morphic effects in simple non magnets to magnetodielectric coupling in multiferroic spinels and hematites. Traditionally, a single spin–phonon coupling constant is used to characterize how effectively the lattice can affect the spin, but it is hardly enough to capture novel electromagnetic behaviors to the full extent. Here, we introduce a concept of spin–phonon dispersion to project the spin moment change along the phonon crystal momentum direction, so the entire spin change can be mapped out. Different from the phonon dispersion, the spin–phonon dispersion has both positive and negative frequency branches even in the equilibrium ground state, which correspond to the spin enhancement and spin reduction, respectively. Our study of bcc Fe and hcp Co reveals that the spin force matrix, that is, the second-order spatial derivative of spin moment, is similar to the vibrational force matrix, but its diagonal elements are smaller than the off-diagonal ones. This leads to the distinctive spin–phonon dispersion. The concept of spin–phonon dispersion expands the traditional Elliott-Yafet theory in nonmagnetic materials to the entire Brillouin zone in magnetic materials, thus opening the door to excited states in systems such as CoF2 and NiO, where a strong spin-lattice coupling is detected in the THz regime.

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Signatures of spin-phonon coupling in hematite crystallites through dielectric and Raman spectroscopy

Cited by 7 publications

References 44 publications

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes

Large Two-Magnon Raman Hysteresis Observed in a Magnetically Uncompensated Hematite Coating across the Morin Transition

Spin–phonon dispersion in magnetic materials

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