Viscous Spin Exchange Torque on Precessional Magnetization in(LaMnO3)2n/(SrMnO3)

Abstract

Photoinduced magnetization dynamics is investigated in chemically ordered (LaMnO3)2n/(SrMnO3)n superlattices using the time-resolved magneto-optic Kerr effect. A monotonic frequency-field dependence is observed for the n=1 superlattice, indicating a single spin population consistent with a homogeneous hole distribution. In contrast, for n> or =2 superlattices, a large precession frequency is observed at low fields indicating the presence of an exchange torque in the dynamic regime. We attribute the emergence of exchange torque to the coupling between two spin populations-viscous and fast spins.

Evolution of magnetic phases and orbital occupation in(SrMnO3)n/(LaMnO3Aruta1, Adamo2, Galdi3 et al. 2009Phys. Rev. B682500View full textAdd to dashboardCite

“…This FM anisotropy resembles that one induced by the magneto-crystalline anisotropy in the LSMO films under tensile strain [21]. The most interesting result is that the anisotropy ratio is larger in the SL with n = 1, where the density of FM interfaces is highest, and decreases with n. Large hysteresis cycles as in our n = 5 and n = 8, already reported in literature for the n = 2, 3 and 5 [8], were explained in terms of competing AFM/FM interactions with magnetic pinning, frustration and canted order. Somehow more surprising is that in all samples we find an important AFM contribution to XLD as shown in Fig.…”

“…In such a case, the metal-insulator transition (MIT) and the magnetic properties depend on the thickness of the constituent blocks [4,5,6,7], although in a non trivial way. Indeed, saturation magnetization does not linearly decrease with n [4] and both fast and viscous spin populations are present, the latter associated to FM/AFM pinning [8]. Therefore, the development of the FM metallic phase at the interfaces is well established and the coexistance of the FM and AFM phases was inferred.…”

“…In this context, strain driven spin-orbital coupled states arising in manganites make the interfaces between these compounds very interesting for engineering unique collective states. As a matter of fact, a certain amount of theoretical and experimental studies on superlattices (SLs) composed by the two AFM insulators, SrMnO 3 (SMO) and LaMnO 3 (LMO), appeared in literature during the last years [4,5,6,7,8,9,10,11,12]. The ordered sequence of the atomic layers in the digital SMO/LMO SLs [4,5], together with the electronic reconstruction arising from the interfacial Mn 3+ /Mn 4+ mixed valence, give rise to peculiar transport, magnetic and orbital properties, when different layering and strain conditions occur.…”

Relaxor characteristics at the interfaces ofNdMnO3/SrMnO3/LaMnO3superlattices

“…The coercive fields along with magnetic moments reveal a critical period of n = 5, indicating the presence of FM phases as previously reported for a similar superlattice of ͓LaMnO 3 / SrMnO 3 ͔. [8][9][10]12 To further investigate the presence of the thermal hyster-PHYSICAL REVIEW B 82, 140405͑R͒ ͑2010͒…”

Strain-engineered magnetic order in (LaMnO3)n/(SrMnO3)Zhang1, Dong2, Wang3 et al. 2012Phys. Rev. B

“…[6][7][8][9][10] For example, La 2/3 Sr 1/3 MnO 3 alloy has a mixed valence of Mn 3+ /Mn 4+ , and the ground state is ferromagnetic half metallic due to the double exchange mechanism. 5 To the contrary, it is found experimentally that cation-ordered (LaMnO 3 ) 2n /(SrMnO 3 ) n (001) superlattices are insulating when n is larger than 3.…”