Discovery of the classical Bose-Einstein condensation of magnons in solid antiferromagnets

Safonov³

2015

Jetp Lett.

Self Cite

The critical conditions for the Bose-Einstein condensation of quasi equilibrium nuclear magnons in the easy-plane antiferromagnets CsMnF 3 and MnCO 3 are theoretically derived. Both systems possess the dynamic frequency shift, the dependence of the precession frequency on the magnetization deflection angle and one is able to observe the magnetic resonance signals in very non-equilibrium conditions when the frequency of pumping is higher than precession frequency. The frequency difference in this case can be compensated by increasing the deflection angle.

mentioning

confidence: 92%

Critical parameters of nuclear magnon Bose–Einstein condensation in systems with dynamic frequency shift

Gazizulin

Safonov³

2015

Jetp Lett.

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“…Within the framework of the Holstein–Primakov paradigm, a magnon gas is considered, which has all the properties of a Bose gas. In a number of works with solid-state magnets, such as CsMnF 27 and MnCO 28 , similar quantum effects of magnonic superfluidity were observed. In these antiferromagnets, coupled nuclear-electron precession is observed.…”

Section: Magnonic Becmentioning

confidence: 63%

Quantum paradigm of the foldover magnetic resonance

Kuzmichev

Safin

et al. 2021

Sci Rep

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The explosive development of quantum magnonics requires the consideration of several previously known effects from a new angle. In particular, taking into account the quantum behavior of magnons is essential at high excitations of the magnetic system, under the conditions of the so-called phenomenon of “foldover” (bi-stable) magnetic resonance. Previously, this effect was considered in the quasi-classical macrospin approximation. However, at large angles of magnetization precession, the magnon density exceeds the critical value for the formation of a magnon Bose condensate (mBEC). Naturally, this purely quantum phenomenon does not exist in the classical approximation. In addition, mBEC leads to superfluid transfer of magnetization, which suppresses the macroinhomogeneity of the samples. The experiments presented in the article show that quantum phenomena well describes the experimental results of nonlinear magnetic resonance in yttrium iron garnet. Thus, we remove the questions that arose earlier when considering this effect without taking into account quantum phenomena. This discovery paves the way for many quantum applications of supermagnonics, such as the magnetic Josephson effect, long-range spin transport, Q-bits, quantum logic, magnetic sensors, and others.

“…The essence of this process is described in detail in the articles [25,26]. After a superfluif 3 He the mBEC and spin superflow were observed in antiferromagnets with coupled nuclearelectron precession CsMnF 3 [27] and MnCO 3 [28,29], where the positive frequency shift from the magnon density takes place.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Quantum Paradigm of the Foldover Magnetic Resonance

Kuzmichev

Safin

et al. 2020

Preprint

The explosive development of quantum magnonics requires considering several previously known effects from a new angle. In this article, we revise the phenomenon of "foldover" (bi-stable) magnetic resonance from the point of view of quantum magnonics. The density of magnons under strong excitation can exceed the critical value for the formation of a magnon Bose condensate. Under these conditions, the effect of quantum transport of magnons should be considered. In particular, the effect of spin superfluidity, discovered earlier in super fluid 3He should lead to spatial redistribution of the precessing magnetization. Our experimental results confirm a significant change in properties of the foldover magnetic resonance in yttrium iron garnet (YIG) due to superfluid magnetization transport. This discovery paves the way for many quantum applications of supermagnonics, such as magnetic Josephson effect, long-distance spin transport, Q-bit, quantum logics, magnetic sensors, and others.