Effects of layered structural features on charge/orbital ordering in (La,Sr)n+1MnnO3n+1(n= 1 and 2)

Ma, Chao; Yang, H. X.; Zeng, Lunjie; Li, Z A; Zhang, Y; Qin, Y. B.; Li, J Q

doi:10.1088/0953-8984/21/4/045601

Cited by 6 publications

(1 citation statement)

References 27 publications

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“…Of these the closest structural analogue to Sr 2 MnO 2 Cu 1.5 S 2 is the n = 1 Ruddlesden–Popper phase La 0.5 Sr 1.5 MnO 4 with a single layer of vertex-linked MnO 6 octahedra . Perovskite-type phases such as Nd 0.5 Sr 0.5 MnO 3 , La 1– x Ca x MnO 3 , and Pr 1– x Ca x MnO 3 , are also well characterized materials in which the CE-type magnetic structure is observed and the n = 2 Ruddlesden–Popper type compound LaSr 2 Mn 2 O 7 is close to this regime. , The adoption of the CE-type magnetic structure in the pure oxide manganites is explained by both checkerboard-type charge order of Mn ions (conveniently described as Mn 3+ and Mn 4+ , but several experimental and theoretical works suggest that the difference in electron count is about 0.1) ,, and in-plane orientational ordering of the first order Jahn–Teller distortion in the Mn 3+ octahedra (so-called orbital ordering). In La 0.5 Sr 1.5 MnO 4 the charge ordering and orbital ordering is evident below a transition at about 220 K, and several experiments have probed the two types of order directly. − In Sr 2 MnO 2 Cu 1.5 S 2 the only long-range structural order apparent in bulk diffraction measurements arises from Cu/vacancy order.…”

Section: Resultsmentioning

confidence: 99%

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr₂MnO₂Cu_1.5(S_1–xSe_x)₂

et al. 2012

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The series Sr2MnO2Cu1.5(S1–x Se x )2 (0 ≤ x ≤ 1) contains mixed-valent Mn ions (Mn2+/Mn3+) in MnO2 sheets which are separated by copper-deficient antifluorite-type Cu2−δCh2 layers with δ ∼ 0.5. The compounds crystallize in the structure type first described for Sr2Mn3Sb2O2 and are described in the I4/mmm space group at ambient temperatures. Below about 250 K, ordering between Cu+ ions and tetrahedral vacancies occurs which is long-range and close to complete in the sulfide-containing end member of the series Sr2MnO2Cu1.5S2 but which occurs over shorter length scales as the selenide content increases. The superstructure is an orthorhombic 2√2a × √2a × c expansion in Ibam of the room temperature cell. For x > 0.3 there are no superstructure reflections evident in the X-ray or neutron diffraction patterns, and the I4/mmm description is valid for the average structure at all temperatures. However, in the pure selenide end member, Sr2MnO2Cu1.5Se2, diffuse scattering in electron diffractograms and modulation in high resolution lattice image profiles may arise from short-range Cu/vacancy order. All members of the series exhibit long-range magnetic order. In the sulfide-rich end member and in compounds with x < 0.1 in the formula Sr2MnO2Cu1.5(S1–x Se x )2, which show well developed superstructures due to long-range Cu/vacancy order, the magnetic structure has a (1/4 1/4 0) propagation vector in which ferromagnetic zigzag chains of Mn moments in the MnO2 sheets are coupled antiferromagnetically in an arrangement described as the CE-type magnetic structure and found in many mixed-valent perovskite and Ruddlesden–Popper type oxide manganites. In these cases the magnetic cell is an a × 2b × c expansion of the low temperature Ibam structural cell. For x ≥ 0.2 in the formula Sr2MnO2Cu1.5(S1–x Se x )2 the magnetic structure has a (0 0 0) propagation vector and is similar to the A-type structure, also commonly adopted by some perovskite-related manganites, in which the Mn moments in the MnO2 sheets are coupled ferromagnetically and long-range antiferromagnetic order results from antiferromagnetic coupling between planes. In the region of the transition between the two different structural and magnetic long-range ordering schemes (0.1 < x < 0.2) the two magnetic structures coexist in the same sample. The evolution of the competition between magnetic ordering schemes and the length scale of the structural order with composition in Sr2MnO2Cu1.5(S1–x Se x )2 suggest that the changes in magnetic and structural order are related consequences of the introduction of chemical disorder.

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Section: Resultsmentioning

confidence: 99%

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr₂MnO₂Cu_1.5(S_1–xSe_x)₂

et al. 2012

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X-ray spectra and valence states of cations in nanostructured half-doped $$\hbox {La}_{0.5}\hbox {Ca}_{0.5}\hbox {MnO}_{3}$$ La 0.5 Ca 0.5 MnO 3 manganite

et al. 2014

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On the origin of transversal current in double-layer heterostructures

Iordanskǐ

2017

Low Temperature Physics

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It is shown that usually used theoretical model for double-layer heterostructures as a pseudospin ferromagnet does not explain the observed two-dimensional spectrum. Its existence is possible when neglecting Coulomb interaction destroying two-dimensional structures and can be realized only in a strong magnetic field. That is connected also with the plain vortex lattices forming in strong magnetic fields due to thermodynamic instability. This model gives reasonable explanations of various observed effects depending on the filling of the corresponding bands. In particular in this work we show that in double-layer heterostructures a large interlayer conductance really observed can exist. Keywords: double-layer heterostructures, two-dimensional spectrum, magnetic fields.The experiments with double-layer heterostructures have a long history beginning from the late eighties of the previous century. The main number of theoretical works [1,2] used the layer index as an additional quasi-spin index. However the experimental work [3] showed that the theoretical results based on this assumption contradict to the performed experiment and require some other description close to the used for one-layer systems [4].We take the coordinate z perpendicular to the plain of the layers and the coordinates = ( , )x y r describe a twodimensional space with a constant electron potential energy ( ) = ( ) U z U z − (see Fig. 1). We assume the existence of a constant magnetic field B directed along z large enough to make the energy of electron Coulomb interaction proportional to B small compared to the magnetic energy proportional to B . That is very important because Coulomb interaction tends to destroy two-dimensional effects. Further we shall neglect Coulomb electron interaction assuming large enough magnetic field.It was shown in the theoretical work [5] for this case the situation is unstable and the creation of plain vortex lattices gives the thermodynamic gain. That is the case of the separate action of the variables z and r, therefore electron wave functions are the products of two functions ( ) ( ).Z z Φ r Various types of the vortex lattices are possible. The electron filling of the proper bands defines the physical properties. The separation of the variables gives two Shrödinger equationswhere ( ) U z is the two-well potential (see Fig. 1). The functions ( ) Φ r are defined by two-dimensional equationHere the effective vector potential eff A includes not only the vector potential of the external magnetic field (1 / 2)[ ] Br but also the contribution of vortices (with the Fig. 1. Interwell potential.

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Effects of layered structural features on charge/orbital ordering in (La,Sr)_n+1Mn_nO_3n+1(n= 1 and 2)

Cited by 6 publications

References 27 publications

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr₂MnO₂Cu_1.5(S_1–xSe_x)₂

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr₂MnO₂Cu_1.5(S_1–xSe_x)₂

X-ray spectra and valence states of cations in nanostructured half-doped $$\hbox {La}_{0.5}\hbox {Ca}_{0.5}\hbox {MnO}_{3}$$ La 0.5 Ca 0.5 MnO 3 manganite

On the origin of transversal current in double-layer heterostructures

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Effects of layered structural features on charge/orbital ordering in (La,Sr)n+1MnnO3n+1(n= 1 and 2)

Cited by 6 publications

References 27 publications

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr2MnO2Cu1.5(S1–xSex)2

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr2MnO2Cu1.5(S1–xSex)2

X-ray spectra and valence states of cations in nanostructured half-doped $$\hbox {La}_{0.5}\hbox {Ca}_{0.5}\hbox {MnO}_{3}$$ La 0.5 Ca 0.5 MnO 3 manganite

On the origin of transversal current in double-layer heterostructures

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Effects of layered structural features on charge/orbital ordering in (La,Sr)_n+1Mn_nO_3n+1(n= 1 and 2)

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr₂MnO₂Cu_1.5(S_1–xSe_x)₂

Competing Magnetic Structures and the Evolution of Copper Ion/Vacancy Ordering with Composition in the Manganite Oxide Chalcogenides Sr₂MnO₂Cu_1.5(S_1–xSe_x)₂