Magnetism and Superconductivity

Aeppli, G.; Flouquet, J.; Gunn, M.; Kjems, Jørgen; Lonzarich, G. G.; Ott, H. R.; Steiner, Myles A.; Vettier, C.

doi:10.1007/978-3-662-04271-7

Cited by 74 publications

(20 citation statements)

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“…The allowed redistribution processes are therefore those preserving the total spin, such as 2 × (m F = 0) ↔ (m F = +1) + (m F = −1). For an isolated system driven to equilibrium only by binary collisions (in contrast with solid-state magnetic materials [14]), and where magnetic dipole-dipole interactions are negligible (in contrast with dipolar atoms [15]), the longitudinal magnetization m z is then a conserved quantity. This conservation law has deep consequences on the thermodynamic phase diagram.…”

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confidence: 99%

Stepwise Bose-Einstein Condensation in a Spinor Gas

et al. 2017

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We observe multi-step condensation of sodium atoms with spin F = 1, where the different Zeeman components mF = 0, ±1 condense sequentially as the temperature decreases. The precise sequence changes drastically depending on the magnetization mz and on the quadratic Zeeman energy q (QZE) in an applied magnetic field. For large QZE, the overall structure of the phase diagram is the same as for an ideal spin 1 gas, although the precise locations of the phase boundaries are significantly shifted by interactions. For small QZE, antiferromagnetic interactions qualitatively change the phase diagram with respect to the ideal case, leading for instance to condensation in mF = ±1, a phenomenon that cannot occur for an ideal gas with q > 0.Multi-component quantum fluids described by a vector or tensor order parameter are often richer than their scalar counterparts. Examples in condensed matter are superfluid 3 He [1] or some unconventional superconductors with spin-triplet Cooper pairing [2]. In atomic physics, spinor Bose-Einstein condensates (BEC) with several Zeeman components m F inside a given hyperfine spin F manifold can display non-trivial spin order at low temperatures [3][4][5][6]. The macroscopic population of the condensate enhances the role of small energy scales that are negligible for normal gases. This mechanism (sometimes termed Bose-enhanced magnetism [6]) highlights the deep connection between Bose-Einstein condensation and magnetism in bosonic gases, and raises the question of the stability of spin order against temperature.In simple cases, magnetic order appears as soon as a BEC forms. Siggia and Ruckenstein [7] pointed out for two-component BECs [7] that a well-defined relative phase between the two components implies a macroscopic transverse spin. BEC and ferromagnetism then occur simultaneously, provided the relative populations can adjust freely. A recent experiment confirmed this scenario for bosons with spin-orbit coupling [8]. This conclusion was later generalized to spin-F bosons without [9] or with spin-independent [10] interactions. These results indicate that without additional constraints, bosonic statistics favors ferromagnetism.In atomic quantum gases with F > 1/2, this type of ferromagnetism competes with spin-exchange interactions, which may favor other spin orders such as spinnematics [6]. Spin-exchange collisions can redistribute populations among the Zeeman states [11][12][13], but are also invariant under spin rotations. The allowed redistribution processes are therefore those preserving the total spin, such as 2 × (m F = 0) ↔ (m F = +1) + (m F = −1). For an isolated system driven to equilibrium only by binary collisions (in contrast with solid-state magnetic materials [14]), and where magnetic dipole-dipole interactions are negligible (in contrast with dipolar atoms [15]), the longitudinal magnetization m z is then a conserved quantity. This conservation law has deep consequences on the thermodynamic phase diagram.The thermodynamics of spinor gases with conserved magnetization has b...

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confidence: 99%

Stepwise Bose-Einstein Condensation in a Spinor Gas

et al. 2017

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“…Two instrumental effects have been studied which may induce a fake non-zero persistent current: offset drifts and offset jumps. A third possible effect, so-called flux jumps [29], did not effect this study.…”

Section: Fake Signalsmentioning

confidence: 71%

Development of a magnetometer-based search strategy for stopped monopoles at the Large Hadron Collider

et al. 2012

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If produced in high energy particle collisions at the LHC, magnetic monopoles could stop in material surrounding the interaction points. Obsolete parts of the beam pipe near the CMS interaction region, which were exposed to the products of pp and heavy ion collisions, were analysed using a SQUID-based magnetometer. The purpose of this work is to quantify the performance of the magnetometer in the context of a monopole search using a small set of samples of accelerator material ahead of the 2013 shutdown.

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“…Very often Landau theory of secondorder phase transitions and mean-field approximation is used to describe the magnetic properties, though this theory may not be able to explain the features near T N because of critical fluctuations near the phase transition [42]. The Gibb's free energy can be written as:…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Magnetic Properties, Magnetic Entropy and Arrot Plot of Antiferromagnetic Frustrated Er2Ti2O7 Compound

Amor

Bejar

Hussein

et al. 2011

J Supercond Nov Magn

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The pyrochlore Er 3+ 2 Ti 4+ 2 O 2− 7 was synthesized via a ceramic method using two different oxides (Er 2 O 3 and TiO 2 ). The compound was found to crystallize in the cubic system with the Fd3m space group (No. 227). A magnetic study, carried out at 2 and 300 K under an applied magnetic field μ 0 H = 0.05 T, has revealed a complex magnetic structure at low temperature. The effective paramagnetic moment μ exp eff , deduced from (χ − χ 0 ) −1 = f (T ) curve, was found by assuming a zero moment on the transition metal atom Ti 4+ . The paramagnetic Curie-Weiss temperature θ CW = −21.54 K, the nearest neighbor interaction J nn = −2.30 K, the classical nearest neighbor J cl = −8.65 K and the dipolar D nn = 3.76 K interactions' values have revealed an antiferromagnetic behavior for Er 2 Ti 2 O 7 compound at low temperature. We have also studied the effects of the magnetic field splitting of rare-earth atom Er 3+ in the compound Er 2 Ti 2 O 7 curved Arrott plots.

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Magnetism and Superconductivity

Cited by 74 publications

References 0 publications

Stepwise Bose-Einstein Condensation in a Spinor Gas

Stepwise Bose-Einstein Condensation in a Spinor Gas

Development of a magnetometer-based search strategy for stopped monopoles at the Large Hadron Collider

Synthesis, Magnetic Properties, Magnetic Entropy and Arrot Plot of Antiferromagnetic Frustrated Er2Ti2O7 Compound

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