arXiv subjects

D. Chandrasekhar Kakarla

Publications and source records attributed to D. Chandrasekhar Kakarla.

3 recordsLinked to original sources

arXiv2025

Successive magnetic transitions and multiferroicity in layered honeycomb BiCrTeO$_{6}$

Low-dimensional magnetic systems based on honeycomb lattices provide a promising platform for exploring exotic quantum phenomena that emerge from the intricate interplay of competing spin, orbital, lattice, and dipolar degrees of freedom. Here, we present a comprehensive study of the layered honeycomb lattice antiferromagnet BiCrTeO$_6$ using magnetization, specific heat, muon spin--relaxation ($μ$SR) spectroscopy, dielectric, pyrocurrent, and high-resolution synchrotron X-ray diffraction (SXRD) measurements. Our results reveal an array of intriguing and strongly correlated phenomena, including two successive antiferromagnetic transitions at $T_{\rm N1}\approx16$ K and $T_{\rm N2}\approx11$ K, a pronounced magnetodielectric coupling effect, and ferroelectric order at $T_{\rm N2}$. Consequently, this compound emerges as a new spin-driven multiferroic system. The SXRD analysis reveals a magnetoelastic-coupling-induced structural phase transition at $T_{\rm N2}$, characterized by a symmetry lowering from P$\bar{3}$1c (163) to P31c (159), which likely triggers the onset of ferroelectricity. In addition to its low-temperature multiferroic behavior, the system exhibits dielectric relaxor characteristics at higher temperatures within the paramagnetic region ($T<50$ K), which is intrinsically linked to the antisite disorder of Cr and Te atoms.

cond-mat.str-el↗

arXiv2025

Coexistence of magnetic and dielectric glassy states in alternating kagome and triangular lattice LuBaCo$_4$O$_7$ cobaltite

To date, the alternating kagome and triangular lattice cobaltites, RBaCo$_4$O$_7$ (R = Ca, Y, and rare earth elements), have been well studied for their large structural distortions, anisotropic exchange interactions, chiral spin liquid states, and giant multiferroic properties. Here, we report the co-existence of magnetic and dielectric glassy states in LuBaCo$_4$O$_7$ below 50 K. AC magnetization studies show an absence of conventional spin-freezing behavior. The cooling and heating in unequal fields (CHUF), thermal cycling, and time-dependent magnetization measurements at low temperature ($T$) show the presence of magnetic glassy state. The $T$-dependent dielectric constant $ε'$ measurements exhibit a strong frequency-independent response at the first-order structural phase transition $T = 160$ K (trigonal $P31c$ to monoclinic $Cc$) and also significant features at the $T = 110$ K (monoclinic $Cc$ to orthorhombic $Pbn2_1$) phase transition. Further, $ε'$ shows a frequency-independent peak at 43 K ($Pbn2_1$) and also dipolar glassy features below 20 K ($Cc$). The non-equilibrium magnetic glassy dynamics and dipolar glassy state at low-$T$ arises from the kinetic arrest of $Cc$ and $Pbn2_1$ phases. From the dielectric probe, we are able to clearly distinguish the kinetically arrested phases at low-$T$ , whereas the bulk magnetization studies are unable to do so as the arrested phases have low magnetic moments.

cond-mat.str-el↗

arXiv2025

Susceptibility anisotropy and absence of ferroelectric order in the Kitaev spin liquid candidate Na$_2$Co$_2$TeO$_6$

We report the magnetic, magnetodielectric, and electric polarization properties of single crystals of the Co-based Kitaev Spin Liquid (KSL) candidate Na$_2$Co$_2$TeO$_6$ (NCTO). The sample shows magnetic transitions at 26 K, 16 K, and 5 K, consistent with the literature. The magnetic measurements along and perpendicular to the Co-honeycomb planes show a strong anisotropy in susceptibility and in Curie-Weiss (C-W) temperatures. The experimental anisotropic C-W temperatures of NCTO qualitatively match with the theoretical C-W temperatures, calculated using the HKTF model [C. Kim \textit{et al.}, J. Phys.: Condens. Matter \textbf{34}, 045802 (2021)]. We find from our temperature- and field-dependent dielectric and pyroelectric ($I_p$) current studies ($H\parallel ab$ and $E\perp ab$) that our single crystal NCTO samples do not have a finite electric polarization below 100 K. These $I_p$ studies confirm the absence of a magnetoelectric coupling and electric polarization properties in the title compound and suggest that the zig-zag AFM structure is more favorable than the triple-$Q$ structure with AFM Kitaev interactions.

cond-mat.str-el↗