Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2504.19803

Unconventional Relaxation Dynamics in Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4: Evidence of Inertial Effects

P. Saha·M. Singh·P. D. Babu·S. Patnaik
View original source ↗Read source document ↗Export metadata ↓

Abstract

Magnetization relaxation dynamics serve as an essential tool for uncovering the intrinsic mechanisms governing the magnetic response and energy dissipation in magnetic systems. In this work, we examine the relaxation dynamics for Beta Mn type Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4 across a frequency range of 1 kHz to 10 kHz, spanning different magnetic phases. While most magnetic systems tend to follow the Debye-like relaxation with non-zero distribution or the Cole-Cole formalism, our analysis reveal that these conventional models fail to capture frequency dependence of ac susceptibility across different magnetic phases in Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4. Instead, an inertial component is needed to successfully describe the dynamics, suggesting the presence of unconventional relaxation behavior. The characteristic relaxation time is found to be of the order of 10^-5 s for both the compositions. The field dependent variation of relaxation time exhibits a non-monotonic nature, with the double peak like structure at the skyrmion phase transitions, implying slower relaxation dynamics at the phase boundaries. Furthermore, the presence of non-zero difference between isothermal and adiabatic susceptibility in the pure phases implies slower relaxation dynamics, which is consistent with the presence of finite dissipation in pure phases. The inertial term has been previously invoked to describe the dynamics in spin ice systems due to the propagation of magnetic monopoles. However, its necessity in this system, points to a wider significance in magnetization dynamics that goes beyond the conventional spin ices and skyrmions.

Explore related subjects

cond-mat.mtrl-scicond-mat.othercond-mat.str-elquant-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P. Saha, M. Singh, P. D. Babu, S. Patnaik. 2025-04-28. Unconventional Relaxation Dynamics in Co_8Zn_7Mn_5 and Co_8Zn_8Mn_4: Evidence of Inertial Effects. https://arxiv.org/abs/2504.19803

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Incommensurate structural and magnetic modulations in potassium-rich cryptomelane, K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$)

Cryptomelane is a hollandite-like material consisting of K$^+$ cations in an $α$-MnO$_2$ tunnel-like crystallographic motif. Cryptomelane with stoichiometry K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$) has been synthesized and its magnetic properties investigated using variable-temperature magnetic susceptibility, heat capacity, and neutron powder diffraction. Three distinct transitions at $T_1=184$\,K, $T_2=54.5$\,K, and $T_3=24$\,K are observed. At $T_1$ there is a subtle tetragonal$\rightarrow$monoclinic transition associated with emergence of a set of non-magnetic superstructure peaks indexable to a $\vec{k}_\mathrm{struc}\approx0.74\vec{c^*}$ incommensurate modulation parallel to the $α$-MnO$_2$ tunnels. Our findings are consistent with a relation previously reported in titanate hollandites, that $x\approx2|\vec{k}_\mathrm{struc}|$. Magnetic Bragg peaks emerge below $T_2=54.5$\,K, and their positions indicate an incommensurate modulated magnetic structure. The model consistent with the data is a dual-$\vec{k}_\mathrm{mag}$ structure with a ferromagnetic $|\vec{k}_\mathrm{mag}|=0$ component and an incommensurate $\vec{k}_\mathrm{mag}\approx0.37\vec{c^*}$, with the latter most likely to be helical. The period of oscillation of the incommensurate magnetic component is in line with predictions based on a Heisenberg spin Hamiltonian [Mandal \textit{et al}. Phys. Rev. B 90, 104420 (2014)]. Below $T_3=24$\,K, there is a magnetic transition, which gives rise to a different set of magnetic Bragg peaks indicative of a highly complex magnetic structure.

cond-mat.mtrl-sci↗
arXiv2026

An anisotropic functional for two-dimensional material systems

Density function theory is the workhorse of modern electronic structure theory. However, its accuracy in practical calculations is limited by the choice of the exchange-correlation potential. In this respect, two-dimensional materials pose a special challenge, as all these materials and their heterostructures have a crucial similarity. The underlying atomic structures are strongly spatially inhomogeneous, implying that current exchange-correlation functionals, that in almost all cases are isotropic, are ill-prepared for an accurate description. We present an anisotropic screened-exchange potential, that remedies this problem and reproduces the band-gap of 2D materials as well as the piecewise linearity of the total energy with fractional occupation number.

cond-mat.mtrl-sci↗
arXiv2026

Thermally-driven reorientation of the Néel vector in altermagnetic MnTe

Altermagnets are novel magnetic systems that possess a spin-polarized electronic band structure without a net magnetic moment, making them promising for device applications. Hexagonal MnTe, a prototypical altermagnet, arguably exhibits the most properties consistent with theoretical predictions, including an anomalous Hall effect despite a vanishing net magnetization, and altermagnetinduced electronic band splitting. However, fundamental questions remain, including why some effects only appear significantly below the magnetic ordering temperature. Here, we resolve this discrepancy by revealing a reorientation of the Néel vector in single-crystalline MnTe. The Néel vector points 30° from the a-axis at low $T$, before aligning directly with the a-axis around $T\simeq 260$ K. We attribute this to single-ion anisotropy, which depends on temperature-dependent lattice parameters. We obtained these results using muon-spin spectroscopy, magnetization measurements, and X-ray diffraction; we show that the findings are consistent with neutron diffraction. Manipulating this effect, for example through strain, could unlock sensitive electronic detection schemes for external stimuli, paving the way for functional altermagnetic devices.

cond-mat.mtrl-sci↗