Stripeless incommensurate magnetism in strongly correlated oxide<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>La</mml:mtext></mml:mrow><mml:mrow><mml:mn>1.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>Sr</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>CoO</mml:mtext></mml:mrow><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>

Savici, A. T.; Zaliznyak, Igor; Gu, Genda; Erwin, R. W.

doi:10.1103/physrevb.75.184443

Cited by 23 publications

(25 citation statements)

References 43 publications

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“…If simply the result of overlapping Lorentzian tails, this implies that the diffuse streaks are yet another signature of the known short-range antiferromagnetic correlations, and further explains why they evolve with the same temperature dependence-opposite the expected behavior for a competing state. In fact, similar diffuse streaks might be expected between Bragg centers due to any mechanism which destabilizes long-range order, regardless of the associated local picture, and would only become more distinct if a 'line Lorentzian' or comparably sophisticated scattering model was employed to properly account for microscopic defect structures 34 . …”

Section: Discussionmentioning

confidence: 91%

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

MacDougall¹,

Aczel²,

Su³

et al. 2016

Phys. Rev. B

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The A-site spinel material, CoAl2O4, is a physical realization of the frustrated diamond-lattice antiferromagnet, a model in which unique incommensurate or 'spin-spiral liquid' ground states are predicted. Our previous single-crystal neutron scattering study instead classified it as a 'kineticallyinhibited' antiferromagnet, where the long ranged correlations of a collinear Néel ground state are blocked by the freezing of domain wall motion below a first-order phase transition at T* = 6.5 K. The current paper provides new data sets from a number of experiments, which support and expand this work in several important ways. We show that the phenomenology leading to the kinetically-inhibited order is unaffected by sample measured and instrument resolution, while new low temperature measurements reveal spin correlations are unchanging between T = 2 K and 250 mK, consistent with a frozen state. Polarized diffuse neutron measurements show several interesting magnetic features, which can be entirely explained by the existence of short-ranged Néel order. Finally, and crucially, this paper presents some of the first neutron scattering studies of single crystalline MnAl2O4, which acts as an unfrustrated analogue to CoAl2O4 and shows all the hallmarks of a classical antiferromagnet with a continuous phase transition to Néel order at TN = 39 K. Direct comparison between the two compounds indicates that CoAl2O4 is unique, not in the nature of high-temperature diffuse correlations, but rather in the nature of the frozen state below T * . The higher level of cation inversion in the MnAl2O4 sample indicates that this novel behavior is primarily an effect of greater next-nearest-neighbor exchange.PACS numbers: 75.30.Ds, 75.50.Lk, 78.70.Nx The A-site spinels, AB 2 X 4 with A magnetic, have seen a surge of interest in the past decade, due to a series of interesting experimental observations 1-15 and theoretical predictions of novel spin-liquid ground states [16][17][18][19][20] . Magnetic cations in these materials comprise a bi-partite diamond lattice, and novel behavior is argued to be the result of a competition between nearest (J 1 ) and nextnearest (J 2 ) neighbor superexchange interactions 2,21 . This is demonstrated explicitly by the calculations of Bergman et al. 16 , who have shown for spin-only materials that the collinear Néel structure favored by J 1 is progressively destabilized with increasing J 2 , until a Lifshitz point is encountered at J2 J1 = 1 8 . For greater J 2 , the ground state is predicted to be a novel 'spiral spin liquid' (SSL) state characterized by fluctuations between an infinitely degenerate set of incommensurate spin spirals, whose propagation wavevectors form a series of calculable manifolds in reciprocal space ('spiral surfaces'). Further calculations [16][17][18] predict that these mass degeneracies are lifted by low-lying thermal or quantum fluctuations, driving first-order phase transitions via the order-by-disorder mechanism 22 to either unique spin spiral or Néel ordered states, depending o...

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Section: Discussionmentioning

confidence: 91%

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

MacDougall¹,

Aczel²,

Su³

et al. 2016

Phys. Rev. B

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“…Locally, the distance between two Ni-centered charge stripes can only amount to an integer multiple but this number has to vary in order to adapt for the non-commensurate charge concentration generating some diffuse scattering. In contrast, along the stripes and thus perpendicular to the stripe modulation the order can be perfect in principle [83].…”

Section: Stripe Order Of Charges and Magnetic Moments In Layered Nickmentioning

confidence: 99%

Neutron scattering studies on stripe phases in non-cuprate materials

Ulbrich

Braden

2012

Physica C: Superconductivity

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Several non-cuprates layered transition-metal oxides exhibit clear evidence for stripe ordering of charges and magnetic moments. Therefore, stripe order should be considered as the typical consequence of doping a Mott insulator, but only in cuprates stripe order or fluctuating stripes coexist with metallic properties. A linear relationship between the charge concentration and the incommensurate structural and magnetic modulations can be considered as the finger print of stripe ordering with localized degrees of freedom. In nickelates and in cobaltates with K 2 NiF 4 structure, doping suppresses the nearest-neighbor antiferromagnetism and induces stripe order. The higher amount of doping needed to induce stripe phases in these non-cuprates series can be attributed to reduced charge mobility. Also manganites exhibit clear evidence for stripe phases with further enhanced complexity, because orbital degrees of freedom are involved. Orbital ordering is the key element of stripe order in manganites since it is associated with the strongest structural distortion and with the perfectly fulfilled relation between doping and incommensurability. Magnetic excitations in insulating stripe phases exhibit strong similarity with those in the cuprates, but only for sufficiently short magnetic correlation lengths reflecting well-defined magnetic stripes that are only loosely coupled.

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“…Despite having different electronic properties to the cuprates, LSCO samples with x = 0.33 and 0.25, which exhibit disordered stripe CO correlations, display the distinctive hourglass magnetic excitation spectrum [31][32][33][34][35][36][37]. However, the origin of the hourglass spectrum and the nature of the CO in this region remain controversial [38][39][40]. The results of μSR and NMR measurements of the x = 1/3 compound revealed the onset of magnetic order within partially disordered charge and spin stripes at around 35 K, with a further glassy freezing of dynamics involving the slow, collective motion of spins within the magnetic stripes at lower temperatures [9].…”

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confidence: 99%

Magnetic phase diagram ofLa2−xSrxCoO4revised using muon-spin relaxation

et al. 2016

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We report the results of a muon-spin relaxation (μSR) investigation of La 2−x Sr x CoO 4 , an antiferromagnetic insulating series which has been shown to support charge ordered and magnetic stripe phases and an hourglass magnetic excitation spectrum. We present a revised magnetic phase diagram, which shows that the suppression of the magnetic ordering temperature is highly sensitive to small concentrations of holes. Distinct behavior within an intermediate x range (0.2 x 0.6) suggests that the putative stripe ordered phase extends to lower x than previously thought. Further charge doping (0.67 x 0.9) prevents magnetic ordering for T 1.5 K.DOI: 10.1103/PhysRevB.93.140406Thirty years after the discovery of high-T c superconductivity, the role of multiple order parameters in the cuprates continues to be a topic of intense research, with the interplay between correlations of charge order (CO), antiferromagnetic spin order (SO), and superconductivity the topic of much investigation [1][2][3][4][5]. Although a detailed comparison of specific systems has been found to be problematical, in order to elucidate the details of the physics at play in a different context it is illuminating to study isostructural nonsuperconducting 3d transition metal oxides [6] such as the antiferromagnetic series La 2−x Sr x CoO 4 (LSCO). Controlled doping of holes into the two-dimensional CoO 2 layers is achieved via substitution of Sr for La but, in contrast to the cuprates, a spin-blockade mechanism means the series remains an insulator for x 1 [7]. The previously reported phase diagram of LSCO, determined by neutron scattering [8], shows a region of nearest-neighbor antiferromagnetism (nnAFM) for low dopant concentrations (x 0.3) and incommensurate (IC) magnetism consistent with stripelike CO and SOs for an intermediate doping range 0.3 x 0.6. Recently, muon-spin rotation (μSR) and NMR measurements made on the stripe ordered x = 1/3 compound [9] revealed the importance of a range of time scales in the magnetic ordering of the material, with μSR showing both the onset of static magnetic order and the freezing of dynamical processes at temperatures significantly lower than the ordering temperature previously identified using neutrons. This is because μSR is sensitive to fluctuations on the microsecond time scale (set by the muon gyromagnetic ratio γ μ = 2π × 135.5 MHz T −1 ). Such slow fluctuations appear static in neutron scattering measurements where the energy resolution E ≈ 1 meV constrains the sensitivity of the technique to fluctuations with a much faster time scale

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Stripeless incommensurate magnetism in strongly correlated oxideLa1.5Sr0.5CoO4

Cited by 23 publications

References 43 publications

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

Neutron scattering studies on stripe phases in non-cuprate materials

Magnetic phase diagram ofLa2−xSrxCoO4revised using muon-spin relaxation

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