Interlayer Magnetoresistance due to Chiral Soliton Lattice Formation in Hexagonal Chiral MagnetCrNb3S6

Abstract

We investigate the interlayer magnetoresistance (MR) along the chiral crystallographic axis in the hexagonal chiral magnet CrNb 3 S 6 . In a region below the incommensurate-commensurate phase transition between the chiral soliton lattice and the forced ferromagnetic state, a negative MR is obtained in a wide range of temperature, while a small positive MR is found very close to the Curie temperature. Normalized data of the negative MR almost falls into a single curve and is well fitted by a theoretical equation of the soliton density, meaning that the origin of the MR is ascribed to the magnetic scattering of conduction electrons by a nonlinear, periodic, and countable array of magnetic soliton kinks. , belong to chiral space groups and are frequently referred to as chiral magnets. In chiral magnets, the combined effect of the symmetric Heisenberg exchange and the antisymmetric Dzyaloshinskii-Moriya (DM) interactions caused by the relativistic spin-orbit interaction [5,6] gives rise to a nontrivial spin texture and various interesting functions unique to chiral magnets. A coupling of conduction electrons with nontrivial spin textures has recently attracted great attention because of the ability to manipulate magnetotransport properties such as the topological Hall effect [7]. One promising candidate to realize this coupling is the chiral soliton lattice (CSL), which is formed in a chiral magnet under magnetic fields perpendicular to the chiral axis. The CSL is a nonlinear array of magnetic soliton kinks. It is naturally expected that each magnetic soliton kink works as a strong scattering potential for itinerant spins. Therefore, decreasing the number of magnetic soliton kinks may reduce the magnetoresistance (MR) and thus the CSL will present a nontrivial MR.In this Letter, we report the MR along the chiral axis in a hexagonal chiral magnetic crystal of CrNb 3 S 6 . We find that the normalized data of the negative MR almost falls into a single curve, and the revealed behavior indicates that the origin of the MR can be attributed to the magnetic scattering of conduction electrons by a nonlinear, periodic, and countable array of magnetic soliton kinks. Namely, we clarify the direct correlation between the experimentally measured MR and the analytically obtained soliton density as a function of the magnetic field.CrNb 3 S 6 is a typical monoaxial chiral magnet, which belongs to the space group of P6 3 22 [8]. It has a layered hexagonal structure of 2H-type NbS 2 intercalated by Cr atoms, so often expressed as Cr 1=3 NbS 2 . The size of the unit cell is 0.57 nm in the ab plane and 1.21 nm along the c axis [9,10]. Cr atoms are in the trivalent state and have localized electrons with spins of S ¼ 3=2, whereas conduction electrons are in an unfilled hybridized band of Nb and S. As a consequence of the chiral space group, the monoaxial DM interaction is allowed along the chiral c axis in CrNb 3 S 6 , which is given in the form of ÀD Á S 1 Â S 2 between localized neighboring spins S 1 and S 2 at Cr atoms. Here, D repres...

Finite-Temperature Properties of Three-Dimensional Chiral Helimagnets

“…Recently, Togawa et al directly observed the CSL structure in CrNb 3 S 6 using Lorentz transmission electron microscopy, and found that the chiral magnetic structures are very stable against crystal defects [11]. With this result, CrNb 3 S 6 is recognized as one * Electronic address: shinozaki@vortex.c.u-tokyo.ac.jp of the candidates of new magnetic devices [12]. In addition to CrNb 3 S 6 , YbNi 3 Al 9 was also discovered as another mono-axial chiral helimagnet with heavy-electron behavior, where the periodicity of the helix is comparable to lattice constant [13][14][15].…”

Incommensurate-commensurate transitions in the monoaxial chiral helimagnet driven by the magnetic field

“…The first three terms give the energy of the conical helix with wave vector q 0 , while the term proportional to β x is the difference between the conical helicoid, (12), and the conical helix. We write the energy in this way for later convenience.…”

“…As * laliena@unizar.es † javier.campo@csic.es the field increases, the regions where the spins rotate slowly become very wide and the regions where the spins rotate rapidly become very narrow, and a chiral soliton lattice (CSL) is formed [1,[5][6][7]. This CSL, which is realized in CrNb 3 S 6 [8], supports dynamic modes like coherent sliding [9] and gives rise to exciting phenomena such as spin motive forces [10] and tunable magnetoresistance [11][12][13][14].…”

Структурное и магнитное упорядочение монокристаллов CrNb-=SUB=-3-=/SUB=-S-=SUB=-6-=/SUB=-, выращенных методом газового транспорта

“…Межслойное магнитосопротивле-ние вдоль оси c дало значение температуры Кюри мо-нокристаллов 132 K [4]. Исследования спин-релаксации µ-мюонов в монокристаллах CrNb 3 S 6 дали оценку T c около 127 K [5].…”

“…Для исследования структуры выращенных кристаллов использовалась дифрактометрическая съем-ка монокристаллов. Различные магнитные методы, при-меняемые ранее для определения температуры Кюри соединения CrNb 3 S 6 [1,[3][4][5] давали отличающиеся друг от друга значения температур ферромагнитного перехо-да. В связи с этим был разработан и применен новый метод оценки температуры ферромагнитного перехода, основанный на температурной и полевой зависимо-стях высокочастотного (ВЧ) поглощения в кристаллах CrNb 3 S 6 в переменном магнитном поле.…”