Uncompensated antiferromagnetic spins at the interface in Mn–Ir based exchange biased bilayers

Tsunoda, Masakiyo; Yoshitaki, S.; Ashizawa, Yoshito; Mitsumata, Chiharu; Nakamura, Tetsuya; Osawa, Hitoshi; Hirono, T.; Kim, D. Y.; Takahashi, M.

doi:10.1063/1.2710216

Cited by 21 publications

(17 citation statements)

References 12 publications

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“…The Mn XAS and XMCD display a lineshape similar to the spectra previously reported in similarly patterned 18 and unpatterned bilayer IrMn films. 17 As expected from the reversed contrast of the Fe and Mn XPEEM images in Fig. 1, we find that the sign of the Mn XMCD spectra is opposite with respect to Fe ͑inset of Fig.…”

supporting

confidence: 58%

“…This AFM coupling is unusual 16 and has been shown to depend on material parameters in IrMn-based systems. 17 In our case, we note that AFM coupling is also observed in structures with uniform magnetization and multiple domain states.…”

mentioning

confidence: 72%

“…This value is consistent with those previously reported for exchange biased films and patterned structures displaying single domain states. 8,17,18 Due to the weighted depth-sensitivity of XPEEM and complex AFM structure of IrMn, we cannot conclude on the persistence of the vortexlike AFM alignment of the Mn spins into the IrMn layer. However, measurements carried out on the reversed layer structure, Ta͑5 nm͒/Cu͑3 nm͒/ NiFe͑12 nm͒/IrMn͑5 nm͒/Al͑1.5 nm͒, exclude the possibility that the uncompensated vortex state extends throughout the IrMn layer.…”

mentioning

confidence: 99%

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Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks

Salazar-Alvarez

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et al. 2009

Applied Physics Letters

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The magnetic domain structure of patterned antiferromagnetic/ferromagnetic Ir20Mn80/Ni80Fe20 bilayer microdisk arrays has been investigated using layer-specific polarized x-ray photoemission electron microscopy and magnetic circular dichroism. Magnetic imaging at the Fe and Mn L-edge resonances provided direct evidence of a vortex state imprinted into the antiferromagnet at the interface. The opposite magnetic contrast between the layers indicated a reversed chirality of the imprinted vortex state, and a quantitative analysis of the magnetic moment from the dichroism spectra showed that uncompensated Mn spins equivalent to about 60% of a monolayer of bulk Ir20Mn80 contributed to the imprinted information at the interface.

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supporting

confidence: 58%

mentioning

confidence: 72%

mentioning

confidence: 99%

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Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks

Salazar-Alvarez

Kavich

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et al. 2009

Applied Physics Letters

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“…What possible factors then remain? Recent studies have pointed out the AF net moment remaining in the interface and the possibility of special conditions for the specific F/AF system [15], and direct observations have also been reported [16,17]. Progress in these approaches is highly desirable.…”

Section: History Of Exchange Magnetic Anisotropy Interpretation and Tmentioning

confidence: 97%

A compensated/uncompensated independent mechanism of exchange anisotropy appearance using a model with loose coupling in the antiferromagnetic region

Sakurai

2011

Elect Comm in Japan

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SUMMARYSince its discovery, unidirectional anisotropy appearing in exchange coupled ferromagnetic (F)/antiferromagnetic (AF) layers has been used to pin ferromagnetic layers of various spin devices. However, a fundamental understanding is still lacking. The author has already demonstrated a mechanism based on simply assuming a loosely coupled layer in the AF region, without imposing any restrictions on the classical Heisenberg spins, with perfect compensated and uncompensated AF interfaces on the simple cubic (sc) lattice. The difference between compensated and uncompensated is only the F/AF coupling form (spin flop or collinear) interaction, and unidirectional anisotropy does not depend on the compensated or uncompensated case, but appears as a result of introducing loose coupling in the AF region. The unidirectional anisotropy energy does not come from the F/AF interfaces, but from the inner AF coupling defects. As reported in our previous papers, a large decrease in AF interaction from 1/10 to 1/1000 of the usual AF interaction was necessary in order to obtain unidirectional anisotropy in the systems. Correspondence between loose coupling and the defect mode, cell size dependency in the fcc system, and thickness dependency are topics for future investigation.

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“…It is attributed that the interfacial Mn spins are polarized due to the exchange coupling with the ferromagnetic Co 70 Fe 30 alloy. 75) Therefore, the uncompensated Mn spins detected by XMCD is very important to solve the origin of the exchange bias effect.…”

Section: Exchange-biased Systemsmentioning

confidence: 99%

Recent Progress of the X-ray Magnetic Circular Dichroism Technique for Element-Specific Magnetic Analysis

Nakamura

Suzuki

2013

J. Phys. Soc. Jpn.

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Recent trend of the X-ray magnetic circular dichroism (XMCD) spectroscopy-based technique and the related scientific topics at SPring-8 are reviewed. At the third-generation synchrotron radiation facility, the key developments in the XMCD technique include i) significant improvements in the accuracy and sensitivity of XMCD measurements with a quick helicity switching of circularly polarized X-rays, ii) introduction of extreme conditions (strong pulsed magnetic field and high pressures), and iii) new experimental setup using the high-brilliance X-ray source (microfocusing, reflection geometry, and high-pressure cells). These achievements have effectively extended the capability of the XMCD technique, a unique magnetic probe with an element-specificity, providing fundamental scientific insights in spintronics and magnetic recording devices, magnetic nanoparticles, and magnetism under high-magnetic field and high pressures.KEYWORDS: X-ray magnetic circular dichroism, element specific magnetic hysteresis, synchrotron radiation X-rays Historical ReviewElement-specific magnetic measurements are widely recognized as a powerful experimental technique for the study of magnetic materials and have previously been exploited mainly by Mössbauer spectroscopy. For the last 30 years, an energy-tunable and polarized X-ray source at synchrotron radiation facilities has given rather expansive possibilities of element-specific magnetic measurements using X-ray spectroscopy. Indeed, X-ray magnetic circular dichroism (XMCD) spectroscopy 1,2) has become one of the leading techniques for element-specific magnetic measurement using a resonant effect in the core-shell absorption with circularly polarized X-ray photons.The XMCD effect was first observed at the Fe K edge in the hard-X-ray region in 1987 by Schütz et al.3) In their experiment, an XMCD spectrum of pure iron was obtained by reversing the direction of magnetic fields applied to a sample, and the circularly polarized X-rays were provided by the off-orbital radiation from a bending magnet (off-plane method).3) The recorded XMCD signal was quite small, of the order of ÁI=I $ 5 Â 10 À3 . Subsequently, XMCD spectra at the L 2;3 edges of rare-earth elements [4][5][6] and at the L 2;3 edges of 5d metals in some alloys with 3d transition metals were also reported. 7) XMCD measurements over a wide energy range that is similar to the extended X-ray absorption fine structure (EXAFS), called magnetic EXAFS, in Fe and Gd 3 Fe 5 O 12 showed a capability of analyses of local magnetic structures using dichroic effects. 8,9) In the soft-X-ray region, the first XMCD spectrum at the Ni L 2;3 edges in a Ni single crystal was reported by Chen et al. in 1990. 10) The circularly polarized soft X-rays were obtained by the off-plain method, similar to the previous XMCD measurement at the Fe K edge.3) The intensity of the observed XMCD signal was about 8% with respect to the resonant absorption, the so called white line, and was much larger than that recorded at the K edge. The strong XMCD value at the...

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Uncompensated antiferromagnetic spins at the interface in Mn–Ir based exchange biased bilayers

Cited by 21 publications

References 12 publications

Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks

Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks

A compensated/uncompensated independent mechanism of exchange anisotropy appearance using a model with loose coupling in the antiferromagnetic region

Recent Progress of the X-ray Magnetic Circular Dichroism Technique for Element-Specific Magnetic Analysis

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