اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدUnexpected phase locking of magnetic fluctuations in the multi-k magnet USb
40
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The spin waves in the multi-k antiferromagnet, USb, soften and become quasielastic well below the AFM ordering temperature, T_N. This occurs without a magnetic or structural transition. It has been suggested that this change is in fact due to de-phasing of the different multi-k components: a switch from 3-k to 1-k behaviour. In this work, we use inelastic neutron scattering with tri-directional polarisation analysis to probe the quasielastic magnetic excitations and reveal that the 3-k structure does not de-phase. More surprisingly, the paramagnetic correlations also maintain the same clear phase correlations well above T_N (up to at least 1.4T_N). This precursor regime has not been observed before in a multi-k system.
قيم البحث
اقرأ أيضاً
Frustrated systems exhibit remarkable properties due to the high degeneracy of their ground states. Stabilised by competing interactions, a rich diversity of typically nanometre-sized phase structures appear in polymer and colloidal systems, while th
e surface of ice pre-melts due to geometrically frustrated interactions. Atomic spin systems where magnetic interactions are frustrated by lattice geometry provide a fruitful source of emergent phenomena, such as fractionalised excitations analogous to magnetic monopoles. The degeneracy inherent in frustrated systems may prevail all the way down to absolute zero temperature, or it may be lifted by small perturbations or entropic effects. In the geometrically frustrated Ising--like magnet Ca3Co2O6, we follow the temporal and spatial evolution of nanoscale magnetic fluctuations firmly embedded inside the spin--density--wave magnetic structure. These fluctuations are a signature of a competing ferrimagnetic phase with an incommensurability that is different from, but determined by the host. As the temperature is lowered, the fluctuations slow down into a super-paramagnetic regime of stable spatiotemporal nano-structures.
Chiral nematic liquid crystals sometimes form blue phases characterized by spirals twisting in different directions. By combining model calculations with neutron-scattering experiments, we show that the magnetic analogue of blue phases does form in t
he chiral itinerant magnet MnSi in a large part of the phase diagram. The properties of this blue phase explain a number of previously reported puzzling features of MnSi such as partial magnetic order and a two-component specific-heat and thermal-expansion anomaly at the magnetic transition.
We present the results of the magnetization and dielectric constant measurements on untwinned single crystal samples of the frustrated S=1/2 chain cuprate LiCu_2O_2. Novel magnetic phase transitions were observed. A spin flop transition of the spiral
spin plane was observed for the field orientations H||a,b. The second magnetic transition was observed at H~15 T for all three principal field directions. This high field magnetic phase is discussed as a collinear spin-modulated phase which is expected for an S=1/2 nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic chain system.
Magnetic skyrmions are vortex-like topological spin textures often observed to form a triangular-lattice skyrmion crystal in structurally chiral magnets with Dzyaloshinskii-Moriya interaction. Recently $beta$-Mn structure-type Co-Zn-Mn alloys were id
entified as a new class of chiral magnet to host such skyrmion crystal phases, while $beta$-Mn itself is known as hosting an elemental geometrically frustrated spin liquid. Here we report the intermediate composition system Co$_7$Zn$_7$Mn$_6$ to be a unique host of two disconnected, thermal-equilibrium topological skyrmion phases; one is a conventional skyrmion crystal phase stabilized by thermal fluctuations and restricted to exist just below the magnetic transition temperature $T_mathrm{c}$, and the other is a novel three-dimensionally disordered skyrmion phase that is stable well below $T_mathrm{c}$. The stability of this new disordered skyrmion phase is due to a cooperative interplay between the chiral magnetism with Dzyaloshinskii-Moriya interaction and the frustrated magnetism inherent to $beta$-Mn.
Exchange bias phenomenon is generally ascribed to the exchange coupling at the interfaces between ferromagnetic and antiferromagnetic layers. Here, we propose a bulk form of exchange bias in a single-phase magnet where the coupling between two magnet
ic sublattices induces a significant shift of the coercive field after a field cooling. Our experiments in a complicated magnet YbFe2O4 demonstrate a giant exchange bias at low temperature when the coupling between the Yb3+ and Fe2+/Fe3+ sublattices take places. The cooling magnetic field dependence and the training effect of exchange bias are consistent with our model. In strong contrast to conventional interfacial exchange bias, this bulk form of exchange bias can be huge, reaching the order of a few Tesla.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
