Determination of the valence of manganese and iron in Mn- and MnZn-ferrites from the shift in x-ray absorption K-edges

Kirichok, P. P.; Kopaev, A. V.; Pashchenko, V. P.

doi:10.1007/bf00897964

Cited by 4 publications

(4 citation statements)

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“…39,40 In the case of the manganites, the K edge energy position has been found to vary with the doping level x between x ¼ 0 (Mn 3þ ) to x ¼ 1 (Mn 4þ ) by about 3.5 eV in LaMn 1Àx Co x O 3 , 41 3-4.2 eV in La 1Àx Ca x MnO 3 , 35-37 2.5-3 eV in La 1Àx Sr x MnO 3 , 42-44 accompanied by other more subtle changes in the spectra, including in peak amplitude and edge shape. Generally speaking, the edge energy position increases from the metallic state (Mn 0 ) to higher formal valence states.…”

Section: Discussionmentioning

confidence: 98%

Control of magnetism in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures (invited)

Vaz

Hoffman

Segal

et al. 2011

Journal of Applied Physics

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Section: Discussionmentioning

confidence: 98%

Control of magnetism in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures (invited)

Vaz

Hoffman

Segal

et al. 2011

Journal of Applied Physics

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“…The main finding is the observation of an energy shift in the Mn absorption edge by +0.3 eV upon switching the PZT polarization from the depletion to the accumulation state. The position of the absorption edge is very sensitive to the cationic valency in a wide array of compounds [23]. In the case of the manganites, the energy edge position is found to vary with the doping level x by about 3.…”

mentioning

confidence: 97%

Origin of the Magnetoelectric Coupling Effect inPb(Zr0.2Ti0.8)O3/La0.8
Vaz
¹
,
Hoffman
²
,
Segal
³

et al. 2010
Phys. Rev. Lett.
331
18
248
1
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The electronic valence state of Mn in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures is probed by near edge x-ray absorption spectroscopy as a function of the ferroelectric polarization. We observe a temperature independent shift in the absorption edge of Mn associated with a change in valency induced by charge carrier modulation in the La0.8Sr0.2MnO3, demonstrating the electronic origin of the magnetoelectric effect. Spectroscopic, magnetic, and electric characterization shows that the large magnetoelectric response originates from a modified interfacial spin configuration, opening a new pathway to the electronic control of spin in complex oxide materials.PACS numbers: 75.70. Cn,78.70.Dm,73.90.+f,75.60.Ej,85.30.Tv,75.30.Kz,85.70.Ay Understanding how to couple the electric and magnetic order parameters in the solid state is a long-standing scientific challenge that is intimately linked to the spatial and temporal symmetries associated with charge and spin. Coupling of the order parameters is observed in many different materials, but the effect is generally weak in magnitude, even in materials that are both ferroelectric and ferromagnetic (multiferroic) [1][2][3]. Increasing the magnitude of the coupling is a fundamental problem in condensed matter physics with important implications for applications. For example, strong magnetoelectric coupling allows for the ultra-sensitive measurement of weak magnetic fields, and at smaller length scales, enables spin-based technologies by allowing the control of the spin state at the atomic scale via electric fields.In single phase multiferroics, the magnetic and ferroelectric orders often occur largely independent of each other, and as a result the magnetoelectric coupling tends to be small [2,4]. In order to overcome this intrinsic limitation in the coupling between the order parameters, artificially structured materials with enhanced magnetoelectric couplings have been engineered, where a break in time reversal and spatial symmetry occurs naturally at the interface between the different phases [3,5,6]. Moreover, the coupling mechanism can be tailored to benefit from several phenomena, including elastic [7,8], magnetic exchange bias [9][10][11], and charge-based [12] couplings. In charge-based multiferroic composites, the sensitivity of the electronic and spin state of strongly correlated oxides to charge provides enhanced coupling between magnetic and ferroelectric order parameters [12]; it often relies on charge doping of a "colossal" magnetoresistive (CMR) manganite to modulate between high and low spin states, which compete for the ground state of the system. However, the microscopic origin of this effect is still not fully understood. In particular, the nature of the effect and how the interplay between charge, spin, and valency combines to yield the large magnetoelectric response in this system remain to be addressed. In this Letter, we explore the sensitivity of x-ray absorption near edge spectroscopy (XANES) to the atomic electronic state to demons...

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“…77,78 In the case of the manganites, the energy edge position has been found to vary with the doping level, x, between x = 0 (Mn 3+ ) to x = 1 (Mn 4+ ) by about 3.5 eV in LaMn 1−x Co x O 3 , 74 3-4.2 eV in La 1−x Ca x MnO 3 , 65-67 2.5-3 eV in La 1−x Sr x MnO 3 . 79-81 Generally speaking, the edge energy position increases from the metallic state (Mn 0 ) to higher formal valence states.…”

Section: Resultsmentioning

confidence: 98%

Electrostatic control of magnetism in all-oxide multiferroic heterostructures

et al. 2010

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Much effort has been devoted recently to designing systems exhibiting simultaneous magnetic and ferroelectric order (multiferroics) with a strong magnetoelectric coupling, which could enable the electrostatic control of magnetism in the solid state. One approach consists of exploring interfacial couplings between magnetic and ferroelectric phases of composite systems, where magnetoelectric couplings larger than those typical of single-phase multiferroics have been achieved. Here, we overview our recent work on epitaxial Pb(Zr 0.2 Ti 0.8 )O 3 /La 0.8 Sr 0.2 MnO 3 (PZT/LSMO) heterostructures tailored to display a large magnetoelectric coupling, which relies on the sensitivity of the magnetic properties of the doped manganites to charge. The magnetoelectric response in this system is hysteretic, displaying abrupt switching between two magnetic states for the two states of the ferroelectric polarization. The microscopic origin of this effect, which is studied using advanced spectroscopic techniques, arises from changes of the valence state of Mn in LSMO induced by the electrostatic modulation in the charge carrier density. Hence, the magnetoelectric coupling in these multiferroic heterostructures is charge-based and electronic in origin. From a quantitative comparison between the measured change in valency and magnetic moment, we conclude that the interfacial spin ordering is modified upon charge doping. This ability to control spin via electric fields opens a new pathway for the development of novel spin-based technologies.

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Determination of the valence of manganese and iron in Mn- and MnZn-ferrites from the shift in x-ray absorption K-edges

Cited by 4 publications

References 10 publications

Control of magnetism in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures (invited)

Control of magnetism in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures (invited)

Origin of the Magnetoelectric Coupling Effect inPb(Zr0.2Ti0.8)O3/La0.8
Vaz
¹
,
Hoffman
²
,
Segal
³

et al. 2010
Phys. Rev. Lett.
331
18
248
1
View full text Add to dashboard Cite

Electrostatic control of magnetism in all-oxide multiferroic heterostructures

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Determination of the valence of manganese and iron in Mn- and MnZn-ferrites from the shift in x-ray absorption K-edges

Cited by 4 publications

References 10 publications

Control of magnetism in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures (invited)

Control of magnetism in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures (invited)

Origin of the Magnetoelectric Coupling Effect inPb(Zr0.2Ti0.8)O3/La0.8Vaz1, Hoffman2, Segal3 et al. 2010Phys. Rev. Lett.331182481View full textAdd to dashboardCite

Electrostatic control of magnetism in all-oxide multiferroic heterostructures

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Origin of the Magnetoelectric Coupling Effect inPb(Zr0.2Ti0.8)O3/La0.8
Vaz
¹
,
Hoffman
²
,
Segal
³

et al. 2010
Phys. Rev. Lett.
331
18
248
1
View full text Add to dashboard Cite