Hourglass Dispersion in Overdoped Single-Layered Manganites

Ulbrich, H.; Steffens, P.; Lamago, D.; Sidis, Y.; Braden, M.

doi:10.1103/physrevlett.108.247209

Cited by 11 publications

(22 citation statements)

References 33 publications

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“…By adding more Sr, it is possible induce extra rows of Mn 4+ ions, changing the periodicity of the structure [133]. Again, an hourglass magnetic dispersion has been reported for Nd 0.33 Sr 1.67 MnO 4 [134].…”

Section: Cobaltates and Manganitesmentioning

confidence: 95%

Spins, stripes, and superconductivity in hole-doped cuprates

Tranquada¹

2013

AIP Conference Proceedings

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Abstract. One of the major themes in correlated electron physics over the last quarter century has been the problem of high-temperature superconductivity in hole-doped copper-oxide compounds. Fundamental to this problem is the competition between antiferromagnetic spin correlations, a symptom of strong Coulomb interactions, and the kinetic energy of the doped carriers, which favors delocalization. After discussing some of the early challenges in the field, I describe the experimental picture provided by a variety of spectroscopic and transport techniques. Then I turn to the technique of neutron scattering, and discuss how it is used to determine spin correlations, especially in model systems of quantum magnetism. Neutron scattering and complementary techniques have determined the extent to which antiferromagnetic spin correlations survive in the cuprate superconductors. One experimental case involves the ordering of spin and charge stripes. I first consider related measurements on model compounds, such as La 2−x Sr x NiO 4+δ , and then discuss the case of La 2−x Ba x CuO 4 . In the latter system, recent transport studies have demonstrated that quasi-two-dimensional superconductivity coexists with the stripe order, but with frustrated phase order between the layers. This has led to new concepts for the coexistence of spin order and superconductivity. While the relevance of stripe correlations to high-temperature superconductivity remains a subject of controversy, there is no question that stripes are an intriguing example of electron matter that results from strong correlations.Keywords: superconductivity, antiferromagnetism, charge order, stripes, cuprates, nickelates, neutron scattering PACS: 78.70.Nx OPENING REMARKSCuprate superconductivity is a fascinating field, with an enormous literature. There have been a great many measurements done on a wide variety of cuprate families. There are numerous theoretical perspectives on the nature of these materials and on the mechanism of superconductivity.I approach this topic not as an unbiased outside observer, but as a participant who has been around from the beginning. My purpose here is not to present a balanced review of all work and perspectives in the field, as there would be too much to cover. Instead, I will present one story about hole-doped cuprates, based largely on experiment and especially on neutron scattering studies. Since one of the main advantages of neutrons is their ability to follow dynamic antiferromagnetic spin correlations, it should come as no surprise that they will play a key role in the story.I have tried to cite sufficient references (especially review articles) so that the curious reader can find further information and potentially a starting point in searching the broader literature. I have not attempted to cite all relevant work, as that would have been

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Section: Cobaltates and Manganitesmentioning

confidence: 95%

Spins, stripes, and superconductivity in hole-doped cuprates

Tranquada¹

2013

AIP Conference Proceedings

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“…This strict rule underlines the dominant role of the orbital ordering in the stripe phases in overdoped manganites. Data were taken from references [22,176,211] for La 1−x Sr 1+x MnO 4 , [194,210] the electronic charge is also found in perovskite materials [180][181][182] so that it can be considered as representative for charge ordered states in manganites. Four different types of superstructure reflections can be identified in half-doped La 0.5 Sr 1.5 MnO 4 [22,182,184].…”

Section: Incommensurate Order Of Charges Spins and Orbitals In Layermentioning

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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“…In the cuprates and cobaltates it has been proposed that the hourglass magnetic excitation spectrum arises due a small ratio of interstripe to intrastripe magnetic interactions, and disorder of the spin interactions [6,7]. The intercharge stripe spin interaction, we tentatively propose for the loss in spectral weight of one mode of the q-1D excitation in the LSNO x = 0.45 material, has a similar role as disorder in producing an hourglass shaped excitation spectrum.…”

mentioning

confidence: 61%

“…For a weak interstripe interaction an hourglass excitation is observed, whereas a strong interaction leads to the symmetric spin wave cones observed in LSNO [3,5]. The role of disorder in wiping out the mode that disperses away from the antiferromagnetic position has been established in a charge stripe ordered manganate, these modes are present at base temperature but they have no measurable intensity on warming to the magnetic ordering temperature [7]. In the case of La 2−x Sr x CoO 4+δ an alternative scenario for the hourglass excitation spectrum arising from disordered checkerboard charge-ordered state has been proposed [8].…”

mentioning

confidence: 98%

Magnetic excitations of the charge stripe electrons below half doping in La2−xSrxNiO4 ( x =<

et al. 2017

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The low energy magnetic excitation spectrum of charge stripe ordered La 2−x Sr x NiO 4 , x = 0.4 and x = 0.45 samples, were studied by neutron scattering. Two excitation modes are observed in both materials, one from the ordered magnetic moments, and a second mode consistent with pseudo-one-dimensional antiferromagnetic excitations of the charge stripe electrons (q-1D). The dispersion of the q-1D excitation follows the same relation as in x = 1/3 composition, with even spectral weight in the two counterpropagating branches of the x = 0.4 sample, however in the x = 0.45 sample only one dispersion branch has any measurable spectral weight. The evolution of the q-1D excitations on doping to the checkerboard charge ordered phase is discussed. DOI: 10.1103/PhysRevB.95.064403 Variation between the hourglass shaped magnetic excitation spectrum of the cuprates compared to the magnetic excitations of charge stripe ordered La 2−x Sr x NiO 4+δ (LSNO) has called into question the relevance of the charge stripe picture for the cuprates [1][2][3][4][5]. Recently however, it has been shown that insulating charge stripe ordered La 5/3 Sr 1/3 CoO 4+δ (LSCoO) has an hourglass shaped magnetic excitation spectrum that can be explained within a similar linear spin wave model used to describe charge stripe ordered LSNO [6]. In the charge stripe model the reason behind the different excitation spectrums is in part due to disorder, but mainly due to the relative strength of the interstripe magnetic interaction across the charge stripe, relative to the the intrastripe interaction [6]. For a weak interstripe interaction an hourglass excitation is observed, whereas a strong interaction leads to the symmetric spin wave cones observed in LSNO [3,5]. The role of disorder in wiping out the mode that disperses away from the antiferromagnetic position has been established in a charge stripe ordered manganate, these modes are present at base temperature but they have no measurable intensity on warming to the magnetic ordering temperature [7]. In the case of La 2−x Sr x CoO 4+δ an alternative scenario for the hourglass excitation spectrum arising from disordered checkerboard charge-ordered state has been proposed [8]. With the recent direct evidence of charge stripe order in La 2−x Sr x CoO 4+δ , the origin of the magnetic hourglass excitation spectrum is in dispute in this material [9].In LSNO magnetic excitations of the charge stripe electrons are observed [10], whereas half-filled charge stripes in the cuprates appear to have no interunit cell spin interactions, and * pgfreeman@uclan.ac.uk the spin state of the charge stripes in LSCoO is effectively S = 0 [1,2]. In the case of the cuprates there is evidence for a Q = 0 intraunit cell magnetic order from certain experimental techniques [11], this is apparently affected by charge stripe order in La-based cuprates possibly indicating the involvement of spins of half-filled stripes [12]. It is necessary to understand the magnetic interactions of the charge stripe electrons in LSNO to throw ligh...

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Hourglass Dispersion in Overdoped Single-Layered Manganites

Cited by 11 publications

References 33 publications

Spins, stripes, and superconductivity in hole-doped cuprates

Spins, stripes, and superconductivity in hole-doped cuprates

Neutron scattering studies on stripe phases in non-cuprate materials

Magnetic excitations of the charge stripe electrons below half doping in La2−xSrxNiO4 ( x =<

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