Charge-orbital ordering and ferromagnetic chains in single-layered manganite crystals

Kimura, T.; Hatsuda, K.; Ueno, Yohtaro; Kajimoto, Ryoichi; Mochizuki, H.; Yoshizawa, H.; Nagai, Takuro; Matsui, Y.; Yamazaki, Atsushi; Tokura, Y.

doi:10.1103/physrevb.65.020407

Cited by 47 publications

(37 citation statements)

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“…In the COO phase, Mn 3+ stripes and Mn 4+ stripes are alternately arranged along the diagonal direction in the a-b plane (MnO 2 plane) with 3x 2 − r 2 /3y 2 − r 2 orbital ordering of Mn 3+ . It was also reported that the charge-orbital states are switched by x between 3x 2 − r 2 /3y 2 − r 2 COO state and 3x 2 − r 2 orbital ordering state in the isostructural Nd 1−x Sr 1+x MnO 4 (0.67 x 1.0) [4]. In the COO phases of the both non-distorted systems, structural modulations based on the MnO 6 Jahn-Teller distortions with the modulation vector q = (1 − x)(a * ± b * )/2 were clearly observed by electron diffraction (ED) measurements [2,5].…”

Section: Introductionmentioning

confidence: 95%

“…A great number of studies have recently been made on various issues in Ruddlesden-Popper manganites (R,A) n+1 Mn n O 3n+1 (R = trivalent lanthanides, A = divalent alkaline-earth ions), such as the charge-orbital ordering (COO) and the tunneling magnetoresistance (TMR) [1][2][3][4][5]. In particular, a real-space ordering pattern of charge and orbital of e g electrons was first directly observed by a resonant X-ray scattering technique for the "n = 1" manganite La 1−x Sr 1+x MnO 4 (x = 0.5) [3].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and structural properties of n= 1 Ruddlesden–Popper manganites Nd1−Ca1+MnO4

Nagai

Yamazaki

Kimoto

et al. 2008

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Synthesis and structural properties of n= 1 Ruddlesden–Popper manganites Nd1−Ca1+MnO4

Nagai

Yamazaki

Kimoto

et al. 2008

Journal of Alloys and Compounds

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“…35 In the range of large doping x > 0.5, higher doping can be reached for Nd 1−x Sr 1+x MnO 4 , while La 1−x Sr 1+x MnO 4 can be doped only up to x ≈ 0.7. In Nd 1−x Sr 1+x MnO 4 samples the C-AF phase was observed 60 for 0.75 < x < 0.9; additionally, a structural phase transition suggesting predominant occupation of directional orbitals along one axis was reported. We found it very encouraging that the same trends have been observed in the MC simulations for two electrons on a √ 8 × √ 8 cluster and for four electrons on a 4 × 4 cluster (x = 3/4), as well as for three electrons on 4 × 4 cluster (x = 0.8125), for large enough J ′ = 0.025t and 0.05t.…”

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Doping dependence of spin and orbital correlations in layered manganites

et al. 2006

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We investigate the interplay between spin and orbital correlations in monolayer and bilayer manganites using an effective spin-orbital t-J model which treats explicitly the eg orbital degrees of freedom coupled to classical t2g spins. Using finite clusters with periodic boundary conditions, the orbital many-body problem is solved by exact diagonalization, either by optimizing spin configuration at zero temperature, or by using classical Monte-Carlo for the spin subsystem at finite temperature. In undoped two-dimensional clusters, a complementary behavior of orbital and spin correlations is found -the ferromagnetic spin order coexists with alternating orbital order, while the antiferromagnetic spin order, triggered by t2g spin superexchange, coexists with ferro-orbital order. With finite crystal field term, we introduce a realistic model for La1−xSr1+xMnO4, describing a gradual change from predominantly out-of-plane 3z 2 − r 2 to in-plane x 2 − y 2 orbital occupation under increasing doping. The present electronic model is sufficient to explain the stability of the CE phase in monolayer manganites at doping x = 0.5, and also yields the C-type antiferromagnetic phase found in Nd1−xSr1+xMnO4 at high doping. Also in bilayer manganites magnetic phases and the accompanying orbital order change with increasing doping. Here the model predicts C-AF and G-AF phases at high doping x > 0.75, as found experimentally in La2−2xSr1+2xMn2O7.

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“…They have been observed in a variety of systems, including nickelates, 1,2,3,4,5,6,7,8 cuprates, 9,10,11,12,13,14,15 and manganites. 16,17,18 Among them, layered La 2−x Sr x CuO 4 (LSCO), La 2−x−y Nd y Sr x CuO 4 (Nd-LSCO), La 2−x Sr x NiO 4 (LSNO), and La 2 NiO 4+δ (LNO) compounds play plausibly the most prominent role. However the similarity between them is superficial only, and the stripes in the cuprates differ from the stripes in the nickelates in many respects.…”

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Microscopic origin of diagonal stripe phases in doped nickelates

2006

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We investigate the electron density distribution and the stability of stripe phases in the realistic two-band model with hopping elements between eg orbitals at Ni sites on the square lattice, and compare these results with those obtained for the doubly degenerate Hubbard model with two equivalent orbitals and diagonal hopping. For both models we determine the stability regions of filled and half-filled stripe phases for increasing hole doping x = 2 − n in the range of x < 0.4, using Hartree-Fock approximation for large clusters. In the parameter range relevant to the nickelates, we obtain the most stable diagonal stripe structures with filling of nearly one hole per atom, as observed experimentally. In contrast, for the doubly degenerate Hubbard model the most stable stripes are somewhat reminiscent of the cuprates, with half-filled atoms at the domain wall sites. This difference elucidates the crucial role of the off-diagonal eg hopping terms for the stripe formation in La2−xSrxNiO4. The influence of crystal field is discussed as well. I. STRIPE PHASES IN NICKELATESStripe phases are one of the most exciting phenomena of modern condensed matter physics. They have been observed in a variety of systems, including nickelates, 1,2,3,4,5,6,7,8 cuprates, 9,10,11,12,13,14,15 and manganites. 16,17,18 Among them, layered La 2−x Sr x CuO 4 (LSCO), La 2−x−y Nd y Sr x CuO 4 (Nd-LSCO), La 2−x Sr x NiO 4 (LSNO), and La 2 NiO 4+δ (LNO) compounds play plausibly the most prominent role. However the similarity between them is superficial only, and the stripes in the cuprates differ from the stripes in the nickelates in many respects. For instance, they are dynamical in the former, and static in the latter. In addition, in Nd-LSCO 9,10,11,12,13,14 and LSCO, 15 one finds the so-called half-filled stripes, with the density of one doped hole per two atoms along the domain wall (DW). In contrast, it is clear from a variety of experiments that magnetic states within doped NiO 2 planes of the nickelates are filled stripes with density of one doped hole per one atom in a DW. 1,2,3,4,5,6,7,8 The question of filling is not the only difference between the nickelate and cuprate stripes, however. Neutron diffraction measurements performed on Nd-LSCO revealed that magnetic peaks are displaced from the antiferromagnetic (AF) maximum at Q AF = π(1, 1) to the points Q s = π(1 ± 2ǫ, 1) and Q s = π(1, 1 ± 2ǫ) and the shift ǫ depends linearly on hole doping x for x < 1/8, while it is almost constant at higher doping. These values correspond to a superposition of vertical (01) and horizontal (10) DWs. The essentially identical modulation and doping dependence of ǫ was observed in superconducting crystals of LSCO with x > 0.05. Conversely, experiments on LSNO established that spin order is characterized by the wave vectors Q s = π(1 ± ǫ, 1 ± ǫ) with ǫ ≃ x for x < 1/3, corresponding to a constant charge of one hole/Ni ion along a diagonal DW, in agreement with the predictions made in the pioneering works by Zaanen and Gunnarsson 19 and others, 20,21,...

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Charge-orbital ordering and ferromagnetic chains in single-layered manganite crystals

Cited by 47 publications

References 16 publications

Synthesis and structural properties of n= 1 Ruddlesden–Popper manganites Nd1−Ca1+MnO4

Synthesis and structural properties of n= 1 Ruddlesden–Popper manganites Nd1−Ca1+MnO4

Doping dependence of spin and orbital correlations in layered manganites

Microscopic origin of diagonal stripe phases in doped nickelates

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