Double-layered monopolar order in the Tb<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>Ti<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>7</mml:mn></mml:msub></mml:math>spin liquid

Sazonov, Andrew; Gukasov, Arsen; Mirebeau, I.; Bonville, P.

doi:10.1103/physrevb.85.214420

Cited by 25 publications

(55 citation statements)

References 34 publications

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“…2 gives D m = 0.48 K. From our theory, the double-layer structure can then be stabilized for D C.m and a displacement of oxygen ions of ∼ 0.6 pm, which are reasonable estimates for multiferroics [8,21]. Using the parametrization of [61] with J = 2.7 K, our multiferroic spin ice model can also explain why the DL phase only appears at finite field [33,50] (Fig. 5).…”

Section: C)mentioning

confidence: 70%

“…Also, Tb 2 Ti 2 O 7 possesses a giant magnetostriction [39,40], especially along the [110] direction [41], and the stability of the low temperature spin liquid phase has been recently ascribed to spin-phonon hybridization of the excitations [42], via dynamical Jahn-Teller coupling [43]. Last but not least, while sample dependence seems to be an issue in this compound, the double-layer structure in a large [110] field has been confirmed by independent experiments [32,33] and is thus a robust feature of Tb 2 Ti 2 O 7 . It should indeed be noted that the nature of the zero-and low-field phases of this material remain under debate -possibly because of light stuffing/dilution [44] -alternatively described as spin liquid [36,37,[45][46][47] or glassy [48][49][50] with antiferromagnetic correlations [50,51].…”

Section: C)mentioning

confidence: 84%

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Multiferroicity in spin ice: Towards magnetic crystallography ofTb2Ti2O7in a field

Jaubert

Moessner

2015

Phys. Rev. B

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We combine two aspects of magnetic frustration, multiferroicity and emergent quasi-particles in spin liquids, by studying magneto-electric monopoles. Spin ice offers to couple these emergent topological defects to external fields, and to each other, in unusual ways, making possible to lift the degeneracy underpinning the spin liquid and to potentially stabilize novel forms of charge crystals, opening the path to a "magnetic crystallography". In developing the general phase diagram including nearest-neighbour coupling, Zeeman energy, electric and magnetic dipolar interactions, we uncover the emergence of a bi-layered crystal of singly-charged monopoles, whose stability, remarkably, is strengthened by an external [110] magnetic field. Our theory is able to account for the ordering process of Tb2Ti2O7 in large field for reasonably small electric energy scales.By providing mechanisms for strong magneto-electric coupling, frustration has become a key ingredient in multiferroics [1][2][3][4][5][6][7][8]. While the search for high-temperature multiferroics is appealing for technological application such as memory devices [8], frustration opens a window on novel fundamental properties of magnetic matter at low temperature where even weak perturbations can play an important role. This holds especially for the collective behaviour of spin liquids in a wide range of compounds from rare-earth [9] and copper [10][11][12] oxides to organic Mott insulators [13] or iridates [14,15].In spin ice materials, the constraints imposed by frustration support an extensively degenerate ground state where magnetic fluxes are locally conserved [16]. Such flux conservation can be described as a divergence-free condition, categorizing the spin ice ground state as a Coulomb spin liquid by analogy with Maxwell's electromagnetism [17][18][19], where excitations take the form of classical magnetic monopoles (Fig. 2.c-d) [20].In addition to their magnetic properties, it has been recently theorized that magnetic monopoles could also carry an electric dipole moment [21] (Fig. 2.c). Here we shall investigate the multiple facets of such magneto-electric coupling, as an unexplored generic ordering process in rare-earth pyrochlores, able to lift the degeneracy of spin liquids and to manipulate topological excitations in frustrated magnets. Our results are double. First of all, we give a precise description of the mosaic of competing phases in our multiferroic spin ice model (Eq. (1)). We show how a ferromagnetic double-layer structure of monopoles (DL) is stabilized by electric dipolar interactions and even enhanced by a magnetic field in the [110] direction. We then use this double-layer structure as a signature of multiferroicity in rare-earth oxides able to account for recent experiments on the spin liquid candidate Tb 2 Ti 2 O 7 in a field.The model -we consider classical Ising spins S aligned with their local easy-axes on the pyrochlore lattice supporting electric moments P induced by magnetoelectric coupling [21] (Fig. 2), interacting via nearest...

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Section: C)mentioning

confidence: 70%

Section: C)mentioning

confidence: 84%

Multiferroicity in spin ice: Towards magnetic crystallography ofTb2Ti2O7in a field

Jaubert

Moessner

2015

Phys. Rev. B

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“…In other words, it consists of a piling along a [111] axis of monopole and antimonopole layers in the Kagome planes, separated by spin ice layers. This "monopole-like" structure bears some resemblance with the field induced antiferromagnetic one observed in Tb 2 Ti 2 O 7 under a high magnetic field oriented along a [110] axis, although the propagation vector is different 33 . It complies with the antiferromagnetic character of the magnetic unit cell through a large number of spin ice defects (namely static monopoles), pre- serving the direction of the staggered magnetization.…”

Section: Neutron Data Analysismentioning

confidence: 86%

Mesoscopic correlations inTb2Ti2O7spin liquid

et al. 2015

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We have studied the spin correlations with k= ( 1 2 , 1 2 , 1 2 ) propagation vector which appear below 0.4 K in Tb2Ti2O7 spin liquid by combining powder neutron diffraction and specific heat on Tb2+xTi2−xO7+y samples with x=0, 0.01, -0.01. The k= ( 1 2 , 1 2 , 1 2 ) order clearly appears on all neutron patterns by subtracting a pattern at 1.2(1) K. Refining the subtracted patterns at 0.07 K yields two possible spin structures, with spin-ice-like and monopole-like correlations respectively. Mesoscopic correlations involve Tb moments of 1 to 2 µB ordered on a length scale of about 20Å. In addition, long range order involving a small spin component of 0.1 to 0.2 µB is detected for the x= 0 and 0.01 samples showing a peak in the specific heat. Comparison with previous single crystals data suggests that the ( 1 2 , 1 2 , 1 2 ) order settles in through nanometric spin textures with dominant spin ice character and correlated orientations, analogous to nanomagnetic twins.Rare earth pyrochlores with geometrical magnetic frustration are model compounds to investigate classical spin ice as well as quantum spin ice physics. The short range ordered ground states with large degeneracy give rise to a large variety of interesting phenomena such as magnetic monopoles 1,2 , first order transition 3 , or unconventional magnetoelastic excitations 4,5 . These frustrated ground states are highly sensitive to small perturbations and to the presence of defects. Already in the 80s, Villain 6 predicted that for an arbitrary small concentration of defects the spinel lattice with pyrochlore structure could switch its ground state from spin liquid to spin glass. More recently many studies focus on the role of a minute amount of defects in pyrochlores. The crystal structure of R 2 Ti 2 O 7 pyrochlores (where R 3+ is a rare earth ion, Ti 4+ is non magnetic) accommodates oxygen vacancies, small off-stoechiometries in the R 3+ or Ti 4+ lattice, "stuffing" or site inversion. Oxygen vacancies introduce Ti 3+ defects instead of Ti 4+ ions, modifying the R 3+ crystal field and inducing local distortions, with various consequences on the low temperature magnetic properties and spin ice physics. In classical spin ice Dy 2 Ti 2 O 7 , oxygen depletion or a low level Dy stuffing in the Ti sites strongly slows down the monopole dynamics at very low temperature 7,8 and affects the nonequilibrium macroscopic properties 9,10 . In the quantum spin ice Yb 2 Ti 2 O 7 , small off-stoechiometry clearly affects the magnetic ground state 11 . It appears that precise studies of the magnetic defects are needed to resolve controversies concerning these unconventional ground states.Among the pyrochlores, Tb 2 Ti 2 O 7 is one of the most complex, the subject of numerous investigations since the discovery of its spin liquid character in 1999. The Tb 3+ short range correlated moments fluctuate 12 down to 20 mK at the time scale of the muon probe (10 −6 s). The origin of these fluctuations has been highly debated [13][14][15][16][17][18] . Several mechanisms have been pr...

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“…In the spin liquid Tb 2 Ti 2 O 7 , where long range magnetic ordering does not occur down to very low temperature in zero field, application of a magnetic field induces magnetic order with k=0 for H // [110] [31] and H // [111] [32], and probably also for H // [001] although no neutron diffraction data are available for this field direction. Actually, for H // [110], an AF structure with k = [100] coexists with the k=0 structure above 2 T and below 1 K [31], but it is not expected to contribute to the magnetisation.…”

Section: Very Low Temperature Isothermal Magnetisation In Tbmentioning

confidence: 99%

“…The occurence of the "spin melting" and the configuration of the β moments are very sensitive to the alignment of the field with respect to the crystal axis. For H // [111], a "spin melting" seems also to occur, but only for one of the 4 Tb sites and at a much lower field [32], and a small misalignment of the field should have practically no effect on the computed curves. Finally, we made an approximation concerning the tetragonal distortion and the magneto-elastic interaction.…”

Section: Very Low Temperature Isothermal Magnetisation In Tbmentioning

confidence: 99%

Magnetization process in Er₂Ti₂O₇at very low temperature

Bonville¹,

Petit²,

Mirebeau³

et al. 2013

J. Phys.: Condens. Matter

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Abstract. We present a model which accounts for the high field magnetisation at very low temperature in two pyrochlore frustrated systems, Er 2 Ti 2 O 7 and Tb 2 Ti 2 O 7 . The two compounds present very different ground states: Er 2 Ti 2 O 7 , which has a planar crystal field anisotropy, is an antiferromagnet with T N =1.2 K, whereas Tb 2 Ti 2 O 7 is expected to have Ising character and shows no magnetic ordering down to 0.05 K, being thus labelled a "spin liquid". Our model is a mean field self-consistent calculation involving the 4 rare earth sites of a tetrahedron, the building unit of the pyrochlore lattice. It includes the full crystal field hamiltonian, the infinite range dipolar interaction and anisotropic nearest neighbour exchange described by a 3-component tensor. For Er 2 Ti 2 O 7 , we discuss the equivalence of our treatment of the exchange tensor, taken to be diagonal in a frame linked to a rare earth -rare earth bond, with the pseudo-spin hamiltonian recently developped for Kramers doublets in a pyrochlore lattice. In Tb 2 Ti 2 O 7 , an essential ingredient of our model is a symmetry breaking developping at very low temperature. We compare its prediction for the isothermal magnetisation with that of "the quantum spin ice" model.

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Double-layered monopolar order in the Tb2Ti2O7spin liquid

Cited by 25 publications

References 34 publications

Multiferroicity in spin ice: Towards magnetic crystallography ofTb2Ti2O7in a field

Multiferroicity in spin ice: Towards magnetic crystallography ofTb2Ti2O7in a field

Mesoscopic correlations inTb2Ti2O7spin liquid

Magnetization process in Er₂Ti₂O₇at very low temperature

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Double-layered monopolar order in the Tb2Ti2O7spin liquid

Cited by 25 publications

References 34 publications

Multiferroicity in spin ice: Towards magnetic crystallography ofTb2Ti2O7in a field

Multiferroicity in spin ice: Towards magnetic crystallography ofTb2Ti2O7in a field

Mesoscopic correlations inTb2Ti2O7spin liquid

Magnetization process in Er2Ti2O7at very low temperature

Contact Info

Product

Resources

About

Magnetization process in Er₂Ti₂O₇at very low temperature