Zigzag and Checkerboard Magnetic Patterns in Orbitally Directional Double-Exchange Systems

Brzezicki, Wojciech; Noce, Canio; Romano, Alfonso; Cuoco, Mario

doi:10.1103/physrevlett.114.247002

Cited by 18 publications

(29 citation statements)

References 48 publications

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“…We have found that double exchange leads to local or global changes of spin-orbital order, similar to formation of orbital stripes [2] or orbital polarons in doped manganites [4]. Such changes are expected to generate novel spin-orbital-charge modulated patterns reported recently for t 2g systems [18].…”

Section: Discussion and Summarysupporting

confidence: 53%

Novel Spin-Orbital Phases Induced by Orbital Dilution

Brzezicki

Cuoco

Oleś

2015

J Supercond Nov Magn

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We demonstrate that magnetic 3d impurities with S = 3/2 spins and no orbital degree of freedom induce changes of spin-orbital order in a 4d 4 Mott insulator with S = 1 spins. Impurities act either as spin defects which decouple from the surrounding ions, or trigger orbital polarons along 3d-4d bonds. The 4d-4d superexchange in the host J host competes with 3d-4d superexchange J imp -it depends on which orbital is doubly occupied. The spinorbital order within the host is totally modified at doping x = 1/4. Our findings provide new perspective for future theoretical and experimental studies of doped transitionmetal oxides. The well-known example are hole-doped La 1−x Sr x MnO 3 manganites with colossal magnetoresistance [3]. At low doping, orbital polarons emerge in an antiferromagnetic (AF) system by double-exchange mechanism [4], while at higher doping, spin order changes globally to a FM metal coexisting with an e g orbital liquid phase [5]. But a different scenario is also possible-frustrated spin-orbital interactions may lead in some cases to the collapse of any long range order and to a spin-orbital liquid suggested for LiNiO 2 [6]. However, spin and orbital energy scales are here quite different, and the reasons behind the absence of magnetic long range order are indeed more subtle and not yet fully understood [7]. KeywordsA rather unique example of a spin-orbital system are perovskite vanadates, where interesting competition between two types of spin-orbital order was observed [8]. The theoretical spin-orbital model describes an interplay between S = 1 spins and τ = 1/2 orbital doublet {yz, zx} active along the c axis [9], while xy orbitals are filled by one electron each. In addition, G-type AF (G-AF) order in YVO 3 is fragile and switches to C-type AF (C-AF) one in Y 1−x Ca x VO 3 [10], with staggered lines of one-dimensional (1D) FM order (Fig. 1), accompanied by G-type alternating orbital (G-AO) order. Already at low doping, x 0.02 finite spectral weight is generated within the Mott-Hubbard gap due to charge defects away from the VO 6 octahedra [11].

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Section: Discussion and Summarysupporting

confidence: 53%

Novel Spin-Orbital Phases Induced by Orbital Dilution

Brzezicki

Cuoco

Oleś

2015

J Supercond Nov Magn

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“…Performing the same procedure for materials in the metallic phase, introducing equation (2) in equation (3) gives…”

Section: Discussionmentioning

confidence: 99%

“…Especially important is the transition to the insulating phase caused by the correlation effects associated with the electron-electron interaction [1]. In the metallic phase near the transition point it has been observed fluctuations and orderings in the spin, charge, and orbital degrees of freedom, properties which are frequently quite different from those of ordinary metals [2,3]. The insulator-to-metal transition could be driven by means of control of key parameters such as band filling or energy bandwidth.…”

Section: Introductionmentioning

confidence: 99%

Insulator-to-metal transition in vanadium supersaturated silicon: variable-range hopping and Kondo effect signatures

García-Hemme¹,

Montero²,

García-Hernansanz³

et al. 2016

J. Phys. D: Appl. Phys.

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We report the observation of the insulator-to-metal transition in crystalline silicon samples supersaturated with vanadium. Ion implantation followed by pulsed laser melting and rapid resolidification produce high quality single-crystalline silicon samples with vanadium concentrations that exceed equilibrium values in more than 5 orders of magnitude. Temperature-dependent analysis of the conductivity and Hall mobility values for temperatures from 10 K to 300 K indicate that a transition from an insulating to a metallic phase is obtained at a vanadium concentration between 1.1 × 10 20 and 1.3 × 10 21 cm −3 . Samples in the insulating phase present a variable-range hopping transport mechanism with a Coulomb gap at the Fermi energy level. Electron wavefunction localization length increases from 61 to 82 nm as the vanadium concentration increases in the films, supporting the theory of impurity band merging from delocalization of levels states. On the metallic phase, electronic transport present a dispersion mechanism related with the Kondo effect, suggesting the presence of local magnetic moments in the vanadium supersaturated silicon material.

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“…Doping Sr onto the Ca sites leads to insulator-to-metal transition accompanied by a changeover from antiferromagnetic to ferromagnetic dominated spin correlations and the occurrence of static magnetic order over nearly the entire range of (Ca,Sr) substitution [31]. To confirm the wide complexity of the phase diagram, novel spin-orbital correlated phenomena [32,33] can be induced by a tiny partial substitution of inequivalent TM ions in the (Sr,Ca)-RP family as observed, for instance, when Ru ions are replaced by Mn [34][35][36][37][38][39][40], Ti [41], Cr [42][43][44][45][46][47], Fe [48], or other transition-metal elements.…”

Section: Introductionmentioning

confidence: 99%

Spin-orbital nature of the high-field magnetic state in theSr4Ru3O10

Granata

Capogna²,

Forte

et al. 2016

Phys. Rev. B

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We perform a spin-polarized neutron-diffraction study to investigate the nature of the high-field magnetic state of the trilayered Sr 4 Ru 3 O 10 . The analysis indicates that a high field applied within the ab plane leads to an unbalance of the spin and orbital moments with a spatial profile that is strongly tied to the layers where the electrons are located in the unit cell. We provide evidence of a layer dependent magnetic anisotropy with the inner layers having larger spin and orbital magnetic moments than the outer ones and show that such behavior is robust to temperature variation being persistent above the Curie temperature. By means of an effective model that includes the coupling between the spin-orbital degrees of freedom at inequivalent Ru sites we ascribe the origin of the layer anisotropy to the cooperative effects between octahedral distortions, spin orbit, and Coulomb interactions.

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Zigzag and Checkerboard Magnetic Patterns in Orbitally Directional Double-Exchange Systems

Cited by 18 publications

References 48 publications

Novel Spin-Orbital Phases Induced by Orbital Dilution

Novel Spin-Orbital Phases Induced by Orbital Dilution

Insulator-to-metal transition in vanadium supersaturated silicon: variable-range hopping and Kondo effect signatures

Spin-orbital nature of the high-field magnetic state in theSr4Ru3O10

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