Exchange-bias feature in core-shell nanoparticles

On the first evidence of exchange-bias feature in magnetically contrasted consolidates made from CoFe 2 O 4 -CoO core-shell nanoparticles.
Nancy Flores-Martinez, Giulia Franceschin, Thomas Gaudisson, Sonia Haj-Khlifa, Sarra Gam Derouich, Nader Yaacoub, Jean-Marc Grenèche, Nicolas Menguy, Raul Valenzuela & Souad Ammar
Scientific Reports 9, 19468 (2019)

Thermal variation of the saturation and remanent magnetizations (a) and that of the coercive and exchange magnetic fields (b) of CFO-CO ceramic, as inferred from its FC hysteresis loops (cooling field of 7 T) recorded at different temperatures.

Ferromagnetic excess moments and apparent exchange bias in FeF 2

Ferromagnetic excess moments and apparent exchange bias in FeF2 single crystals 
D. C. Joshi, P. Nordblad, R. Mathieu
Scientific Reports 9, 18884 (2019)

Temperature dependence of (a) magnetization M under FC in a magnetic field of H = 5 Oe, and (b) thermo-remnant magnetization (TRM) measured along perpendicular (⊥c), 45° and parallel to c-axis (||c) of the FeF2 circular disc. The inset shows a photograph of the top view (along the c-axis) of the FeF2 single crystal used in experiment.

Tuning EB by control of interface coupling

Tuning the coercivity and exchange bias by controlling the interface coupling in bimagnetic core/shell nanoparticles.
Gabriel C. Lavorato, Enio Lima, Jr., Horacio E. Troiani, Roberto D. Zysler and Elin L. Winkler
Nanoscale 9, 10240 (2017)

Rev. Mod. Phys. 89, 025006 (2017) - Interface-induced phenomena in magnetism

Interface-induced phenomena in magnetism.
Frances Hellman et al.Rev. Mod. Phys. 89, 025006 (2017)

Role of the antiferromagnetic bulk spins in exchange bias

Role of the antiferromagnetic bulk spins in exchange bias.
Ivan K. Schuller, Rafael Morales, Xavier Batlle, Ulrich Nowak, Gernot Güntherodt
JMMM 416, 2 (2016)

Interplay between anisotropy and EB in films

Interplay between magnetocrystalline anisotropy and exchange bias in epitaxial CoO/Co films.
Hao-Liang Liu, Steven Brems, Yu-Jia Zeng, Kristiaan Temst, André Vantomme and Chris Van Haesendonck
Journal of Physics: Condensed Matter 28, 196002 (2016)

EB by field-induced spin reconfiguration in Ni-Mn-Sn

Exchange bias caused by field-induced spin reconfiguration in Ni-Mn-Sn.
A. Çakır, M. Acet, and M. Farle
Phys. Rev. B 93, 094411 (2016)

$M-H$ curves for $x=10.1$ between 10 and 70 K. Open and closed symbols represent FC and ZFC measurements, respectively.

Tunable exchange bias in dilute magnetic alloys – chiral spin glasses

Tunable exchange bias in dilute magnetic alloys – chiral spin glasses

Matthias Hudl, Roland Mathieu and Per Nordblad

Scientific Reports 6, 19964 (2016)

(a) The central part of M vs. H loops after cooling the sample in H_FC to 5 K, and measure the hysteresis loop on decreasing the field to – H_FC and back to +H_FC. The insets show the field dependence of the parameter H_sw1, H_sw2, (right) and ΔM (left) in the H_FC range 1 to 9 T. (b) Full hysteresis loops measured at 5 K from 0 to 14, 14 to −14 and then back +14 T. The inset shows the central part of the loop and the fields H_sw1 and H_sw2 are marked. The jump and definition of the excess magnetization, ΔM, is indicated in the main frame. (c,d) The central part of the hysteresis loops measured after field cooling (c) and zero field cooling (d) in fields up to 5 T at 5 K. The arrows indicate the initial field sweep direction. (Red loops- positive initial fields, blue loops - negative initial fields).

Magnetization reversal of an individual exchange-biased permalloy nanotube

Magnetization reversal of an individual exchange-biased permalloy nanotube.

A. Buchter, R. Wölbing, M. Wyss, O. F. Kieler, T. Weimann, J. Kohlmann, A. B. Zorin, D. Rüffer, F. Matteini, G. Tütüncüoglu, F. Heimbach, A. Kleibert, A. Fontcuberta i Morral, D. Grundler, R. Kleiner, D. Koelle, and M. Poggio

Phys. Rev. B 92, 214432 (2015)

Training effect: (a) SQUID and (b) DCM hysteresis loops for different loop number n at T=3.4 K. Red and blue curves indicate up- and down-sweep, respectively. Evolution of (c) exchange field and (d) coercivity with increasing loop number n extracted from SQUID data set. Dashed line fits the data according to Eq. (2). Point size corresponds to the measurement error in field

Criteria for saturated magnetization loop

Criteria for saturated magnetization loop.

A. Harres, M. Mikhov, V. Skumryev, A.M.H. de Andrade, J.E. Schmidt, J. Geshev

J. Magn. Magn. Mater.402, 76 (2015)

M(H  ) loops calculated for a disordered system of non-interacting single-domain uniaxial-anisotropy particles using $H_{\max }^{+}/H_{\mathrm{A}}=1.2$, where $H_{\max }^{-}/H_{\mathrm{A}}=-1.2$ (panel (a)) and $H_{\max }^{-}/H_{\mathrm{A}}=-0.8$ (panel (b)). The first (panels (c) and (d)) and the second (panels (e) and (f)) derivatives of the respective descending and ascending branches for negative fields are also given. Although $H_{\max }^{+}/H_{\mathrm{A}}=1.2$ for both loops and their derivatives, only the regions of interest are plotted. The bottom panels show the −m_d(H)$-m_{\mathrm{d}}\left(H\right)$ and m_r(H)$m_{\mathrm{r}}\left(H\right)$ (the latter obtained starting from a random magnetization state) remanence curves; the first derivatives of −m_d(H)$-m_{\mathrm{d}}\left(H\right)$ are plotted in the insets.

Competing domains in EB nanostrucutres

Manipulation of competing ferromagnetic and antiferromagnetic domains in exchange-biased nanostructures.
Arantxa Fraile Rodríguez, Ali C. Basaran, Rafael Morales, Miroslavna Kovylina, Jordi Llobet, Xavier Borrisé, Matthew A. Marcus, Andreas Scholl, Ivan K. Schuller, Xavier Batlle, and Amílcar Labarta
Phys. Rev. B 92, 174417 (2015)

Fraction of inverted domains for Ni(6nm)/FeF2(70nm) as a function of the AD, measured at zero field and 30 K, upon ZFC from 296 K (red) and FC (black; HFC=50Oe from 200 K to 45 K and HFC=0Oe from 45 K to 30 K). The error bars represent the standard deviation over up to 15 independent measurements. The occasional data points where no error bar is given refer as to cases where a comparable statistics is not available. The dashed lines are guides to the eye.

Exchange bias in molecular layers

Exchange bias and room-temperature magnetic order in molecular layers.

Manuel Gruber, Fatima Ibrahim, Samy Boukari, Hironari Isshiki, Loïc Joly, Moritz Peter, Michał Studniarek, Victor Da Costa, Hashim Jabbar, Vincent Davesne, Ufuk Halisdemir, Jinjie Chen, Jacek Arabski, Edwige Otero, Fadi Choueikani, Kai Chen, Philippe Ohresser, Wulf Wulfhekel, Fabrice Scheurer, Wolfgang Weber, Mebarek Alouani, Eric Beaurepaire & Martin Bowen

Nature Materials 14, 981 (2015)

Adsorption geometry and magnetic properties of the MnPc stacking on Co deduced from DFT calculations.

 

EB in spin glass/ferromagnet bilayers

Cooling field and temperature dependent exchange bias in spin glass/ferromagnet bilayers.
W. B. Rui, Y. Hu, A. Du, B. You, M. W. Xiao, W. Zhang, S. M. Zhou, J. Du
Scientific Reports 5, 13640 (2015)

(a) The M-H hysteresis loops measured under H_FC = 0.2 kOe and 50 kOe at T = 2 K for a Fe₁₁Au₈₉(50 nm)/FeNi(5 nm) sample, (b) the calculated M-H hysteresis loops under H_FC = 0.2 kOe and 50 kOe at T = 2.6 K for the SG/FM bilayers, and the experimental (c) and calculated (d) cooling field dependences of low-temperature H_E and H_C.

EB in molecular layers

Exchange bias and room-temperature magnetic order in molecular layers.

Manuel Gruber, Fatima Ibrahim, Samy Boukari, Hironari Isshiki, Loïc Joly, Moritz Peter, Michał Studniarek, Victor Da Costa, Hashim Jabbar, Vincent Davesne, Ufuk Halisdemir, Jinjie Chen, Jacek Arabski, Edwige Otero, Fadi Choueikani, Kai Chen, Philippe Ohresser, Wulf Wulfhekel, Fabrice Scheurer, Wolfgang Weber, Mebarek Alouani, Eric Beaurepaire, Martin Bowen

Nature Materials 14, 981 (2015)

The red arrows represent the orientation of the spin moments. Note that the third layer dominantly exhibits a paramagnetic behaviour. The left inset represents the second-ML molecule on top of the semi-transparent first-ML molecule. The right inset shows the relative alignment of the second-ML molecule (semi-transparent) to the third-ML molecule.

Exchange bias in Au-Fe3O4 dumbbell NPs

Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold.
Mikhail Feygenson, John C. Bauer, Zheng Gai, Carlos Marques, Meigan C. Aronson, Xiaowei Teng, Dong Su, Vesna Stanic, Volker S. Urban, Kevin A. Beyer, and Sheng Dai
Phys. Rev. B 92, 054416 (2015)

Temperature-dependent ZFC and FC magnetizations for (a) Au-4 sample and (b) free solution of Fe3O4 and Au nanoparticles. The field-dependent magnetization measured after field cooling in 50 kOe from 300 K for (c) Au-4 and (d) reference samples at various temperatures. Inset: the same plot at lower fields, showing no horizontal shift of the hysteresis loop.

AF proximity effect in Co NPs

High Temperature Magnetic Stabilization of Cobalt Nanoparticles by an Antiferromagnetic Proximity Effect.
José A. De Toro, Daniel P. Marques, Pablo Muñiz, Vassil Skumryev, Jordi Sort, Dominique Givord, and Josep Nogués

Phys. Rev. Lett. 115, 057201 (2015)

(a) Schematic representation of the Co/CoO−NiO sample. (b) Field-cooled hysteresis loops of the Co/CoO−NiO samples (S series) at 10 K. Shown in the inset is the 10-K hysteresis loop of R80. (c) Field-cooled hysteresis loops of the same samples at 300 K. Shown in the inset are the same loops up to higher fields.

Size effects on EB in NiO NPs

Scrutinizing the role of size reduction on the exchange bias and dynamic magnetic behavior in NiO nanoparticles.
N Rinaldi-Montes, P Gorria, D Martínez-Blanco, A B Fuertes, L Fernández Barquín, I Puente-Orench and J A Blanco
Nanotechnology 26, 305705 (2015)

(a)–(d) Magnetic hysteresis loops for samples D2, D4 and D9 measured at selected temperatures, (a) 2, (b) 20, (c) 140 and (d) 300 K (that corresponding to a bulk NiO standard is included for the sake of comparison). (e)–(h) Enlarged views of the central part of the loops, evidencing the decrease in H_C and M_r with increasing temperature. The pictures inside (a)–(d) indicate the blocked/frozen (blue) or unblocked/unfrozen (red) regimes for the cores and shells, and correspond to samples D2 (top), D4 (middle) and D9 (bottom)

 

Heusler alloys for giant exchange bias

Design of compensated ferrimagnetic Heusler alloys for giant tunable exchange bias.
Ajaya K. Nayak, Michael Nicklas, Stanislav Chadov, Panchanana Khuntia, Chandra Shekhar, Adel Kalache, Michael Baenitz, Yurii Skourski, Veerendra K. Guduru, Alessandro Puri, Uli Zeitler, J. M. D. Coey & Claudia Felser
Nature Materials 14 679 (2015)

a, Uncompensated magnetization, M, in Mn_3−xPt_xGa going through a compensation point (M = 0) at x = 0.59 (upper panel): squares are results from theoretical calculations. The line is a guide to eye. Lower panel: Experimental EB field H_EB…

 

Design of compensated ferrimagnetic Heusler alloys for giant tunable exchange bias : Nature Materials : Nature Publishing Group

Design of compensated ferrimagnetic Heusler alloys for giant tunable exchange bias.
Ajaya K. Nayak, Michael Nicklas, Stanislav Chadov, Panchanana Khuntia, Chandra Shekhar, Adel Kalache, Michael Baenitz, Yurii Skourski, Veerendra K. Guduru, Alessandro Puri, Uli Zeitler, J. M. D. Coey, Claudia Felser
Nature Materials 14, 679 (2015) 

a, Uncompensated magnetization, M, in Mn_3−xPt_xGa going through a compensation point (M = 0) at x = 0.59 (upper panel): squares are results from theoretical calculations. The line is a guide to eye. Lower panel: Experimental EB field H_EB at 4.2 K (solid circles). The solid line corresponds to the result of our calculation. The regular and inverse Heusler structures of the Mn₃Ga and Mn₂PtGa are shown to the left and right respectively. b–d, Magnetic moments of Mn in two different sublattices for Mn₃Ga, Mn_2.41Pt_0.59Ga and Mn₂PtGa. Red arrows correspond to Mn in the Mn–Ga plane and blue arrows to Mn in the Mn–Mn planes. The size and direction of the moment is indicated by the arrow. Perfect magnetic compensation is expected in Mn_2.41Pt_0.59Ga. e, FM domains (boundaries indicated by dashed lines) inside the compensated AFM host.

Bimodal distribution of blocking temperature for exchange-bias ferromagnetic/antiferromagnetic bilayers: a granular Monte Carlo study with less stable magnetic regions spread over the interface - References - Journal of Physics D: Applied Physics - IOPscience

Bimodal distribution of blocking temperature for exchange-bias ferromagnetic/antiferromagnetic bilayers: a granular Monte Carlo study with less stable magnetic regions spread over the interface - References - Journal of Physics D: Applied Physics - IOPscience