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In this study, we identify EuCd2X2 (for X = P, As, Sb) as a series of magnetic semiconductors. We examine how the band gap of the series responds to X changing from phosphorus (P), to arsenic (As), and finally antimony (Sb). We characterize the samples using electronic transport and magnetization measurements. Based on infrared spectroscopy, we find that the band gap reduces progressively from 1.23 eV in EuCd2P2, to 0.77 eV in EuCd2As2, and finally 0.52 eV in EuCd2Sb2. In a magnetic field, all three systems show a strong response and their band gaps decrease at 4 K. This decrease is non-monotonic as we change X. It is strongest in the phosphorous compound and weakest in the antimony compound. For all the three compositions, EuCd2X2 remains a semiconductor up to the highest magnetic field applied (16 T).

Murunskite (K$_2$FeCu$_3$S$_4$) is a bridging compound between the only two known families of high-temperature superconductors. It is a semiconductor like the parent compounds of cuprates, yet isostructural to metallic iron-pnictides. Moreover, like both families, it has an antiferromagnetic (AF)-like response with an ordered phase occurring below $\approx$ 100 K. Through comprehensive neutron, M\"ossbauer, and XPS measurements on single crystals, we unveil AF with a nearly commensurate quarter-zone wave vector. Intriguingly, the only identifiable magnetic atoms, iron, are randomly distributed over one-quarter of available crystallographic sites in 2D planes, while the remaining sites are occupied by closed-shell copper. Notably, any interpretation in terms of a spin-density wave is challenging, in contrast to the metallic iron-pnictides where Fermi-surface nesting can occur. Our findings align with a disordered-alloy picture featuring magnetic interactions up to second neighbors. Moreover, in the paramagnetic state, iron ions are either in Fe$^{3+}$ or Fe$^{2+}$ oxidation states, associated with two distinct paramagnetic sites identified by M\"ossbauer spectroscopy. Upon decreasing the temperature below the appearance of magnetic interactions, these two signals merge completely into a third, implying an orbital transition. It completes the cascade of (local) transitions that transform iron atoms from fully orbitally and magnetically disordered to homogeneously ordered in inverse space, but still randomly distributed in real space., Comment: 17 pages, 8 figure, 2 tables (9 pages, 4 figures in the main text; 8 pages, 4 figures, 2 tables in the appendix)

Quantum spin liquids (QSLs) have become a key area of research in magnetism due to their remarkable properties, such as long-range entanglement, fractional excitations, pinch-point singularities, and topologically protected phenomena. In recent years, the search for QSLs has expanded into the three-dimensional world, where promising features have been found in materials that form pyrochlore and hyper-kagome lattices, despite the suppression of quantum fluctuations due to high dimensionality. One such material is the $S = 1$ K$_2$Ni$_2$(SO$_4$)$_3$ compound, which belongs to the langbeinite family consisting of two interconnected trillium lattices. Although magnetically ordered, K$_2$Ni$_2$(SO$_4$)$_3$ has been found to exhibit a highly dynamical and correlated state which can be driven into a pure quantum spin liquid under magnetic fields of only $B \simeq 4$~T. In this article, we combine inelastic neutron scattering measurements with pseudo-fermion functional renormalization group (PFFRG) and classical Monte Carlo (cMC) calculations to study the magnetic properties of K$_2$Ni$_2$(SO$_4$)$_3$, revealing a high level of agreement between the experiment and theory. We further reveal the origin of the dynamical state in K$_2$Ni$_2$(SO$_4$)$_3$ by studying a larger set of exchange parameters, uncovering an `island of liquidity' around a focal point given by a magnetic network composed of tetrahedra on a trillium lattice.

EuCd$_2$As$_2$ is now widely accepted as a topological semimetal in which a Weyl phase is induced by an external magnetic field. We challenge this view through firm experimental evidence using a combination of electronic transport, optical spectroscopy and excited-state photoemission spectroscopy. We show that the EuCd$_2$As$_2$ is in fact a semiconductor with a gap of 0.77 eV. We show that the externally applied magnetic field has a profound impact on the electronic band structure of this system. This is manifested by a huge decrease of the observed band gap, as large as 125~meV at 2~T, and consequently, by a giant redshift of the interband absorption edge. However, the semiconductor nature of the material remains preserved. EuCd$_2$As$_2$ is therefore a magnetic semiconductor rather than a Dirac or Weyl semimetal, as suggested by {\em ab initio} computations carried out within the local spin-density approximation., Comment: Accepted for publication in Physical Review Letters

Using small-angle neutron scattering (SANS), we investigate the deformation of the magnetic skyrmion lattice in bulk single-crystalline MnSi under electric current flow. A significant broadening of the skyrmion-lattice-reflection peaks was observed in the SANS pattern for current densities greater than a threshold value j_t ~ 1 MA/m^2 (10^6 A/m^2). We show this peak broadening to originate from a spatially inhomogeneous rotation of the skyrmion lattice, with an inverse rotation sense observed for opposite sample edges aligned with the direction of current flow. The peak broadening (and the corresponding skyrmion lattice rotations) remain finite even after switching off the electric current. These results indicate that skyrmion lattices under current flow experience significant friction near the sample edges, and plastic deformation due to pinning effects, these being important factors that must be considered for the anticipated skyrmion-based applications in chiral magnets at the nanoscale.

Due to their topological protection and nanometric size, magnetic skyrmions are anticipated to form components of new high-density memory technologies. In metallic systems skyrmion manipulation is achieved easily under a low density electric current flow, although the inevitable thermal dissipation ultimately limits the energy efficacy of potential applications. On the other hand, a near dissipation-free skyrmion and skyrmion phase manipulation is expected by using electric \emph{fields}, thus meeting better the demands of an energy-conscious society. In this work on an insulating chiral magnet Cu$_{2}$OSeO$_{3}$ with magnetoelectric coupling, we use neutron scattering to demonstrate directly i) the creation of metastable skyrmion states over an extended range in magnetic field and temperature, and ii) the in-situ electric field-driven switching between topologically distinct phases; the skyrmion phase and a competing non-topological cone phase. For our accessible electric field range, the phase switching is achieved in a high temperature regime, and the remnant (E=0) metastable skyrmion state is thermally volatile with an exponential lifetime on hour timescales. Nevertheless, by taking advantage of the demonstrably longer-lived metastable skyrmion states at lower temperatures, a truly non-volatile and near dissipation-free topological phase change memory function is promised in magnetoelectric chiral magnets.

We report magnetic and thermodynamic properties of a $4d^1$ (Mo$^{5+}$) magnetic insulator MoOPO$_4$ single crystal, which realizes a $J_1$-$J_2$ Heisenberg spin-$1/2$ model on a stacked square lattice. The specific-heat measurements show a magnetic transition at 16 K which is also confirmed by magnetic susceptibility, ESR, and neutron diffraction measurements. Magnetic entropy deduced from the specific heat corresponds to a two-level degree of freedom per Mo$^{5+}$ ion, and the effective moment from the susceptibility corresponds to the spin-only value. Using {\it ab initio} quantum chemistry calculations we demonstrate that the Mo$^{5+}$ ion hosts a purely spin-$1/2$ magnetic moment, indicating negligible effects of spin-orbit interaction. The quenched orbital moments originate from the large displacement of Mo ions inside the MoO$_6$ octahedra along the apical direction. The ground state is shown by neutron diffraction to support a collinear N\'eel-type magnetic order, and a spin-flop transition is observed around an applied magnetic field of 3.5 T. The magnetic phase diagram is reproduced by a mean-field calculation assuming a small easy-axis anisotropy in the exchange interactions. Our results suggest $4d$ molybdates as an alternative playground to search for model quantum magnets., Comment: 9 pages, 7 figures

We have used inelastic neutron scattering to measure the magnetic excitation spectrum along the high-symmetry directions of the first Brillouin zone of the magnetic skyrmion hosting compound Cu$_2$OSeO$_3$. The majority of our scattering data are consistent with the expectations of a recently proposed model for the magnetic excitations in Cu$_2$OSeO$_3$, and we report best-fit parameters for the dominant exchange interactions. Important differences exist, however, between our experimental findings and the model expectations. These include the identification of two energy scales that likely arise due to neglected anisotropic interactions. This feature of our work suggests that anisotropy should be considered in future theoretical work aimed at the full microscopic understanding of the emergence of the skyrmion state in this material., Comment: 5 pages, 6 figures

We report the synthesis of single crystals of a novel layered iridate Ba$_{21}$Ir$_9$O$_{43}$, and present the crystallographic, transport and magnetic properties of this material. The compound has a hexagonal structure with two iridium oxide layers stacked along the $c$ direction. One layer consists of a triangular arrangement of Ir$_2$O$_9$ dimers while the other layer comprises two regular octahedra and one triangular pyramid, forming inter-penetrated triangular lattices. The resistivity as a function of temperature exhibits an insulating behavior, with a peculiar $T^{-3}$ behavior. Magnetic susceptibility shows antiferromagnetic Curie-Weiss behavior with $\Theta_\mathrm{CW} \simeq -$90 K while a magnetic transition occurs at substantially lower temperature of 9 K. We discuss possible valence states and effective magnetic moments on Ir ions in different local environments, and argue that the Ir ions in a unique triangular-pyramidal configuration likely carry unusually large magnetic moments., Comment: 5 pages, 3 figures

The recent discovery of magnetic skyrmion lattices initiated a surge of interest in the scientific community. Several novel phenomena have been shown to emerge from the interaction of conducting electrons with the skyrmion lattice, such as a topological Hall-effect and a spin-transfer torque at ultra-low current densities. In the insulating compound Cu2OSeO3, magneto-electric coupling enables control of the skyrmion lattice via electric fields, promising a dissipation-less route towards novel spintronic devices. One of the outstanding fundamental issues is related to the thermodynamic stability of the skyrmion lattice. To date, the skyrmion lattice in bulk materials has been found only in a narrow temperature region just below the order-disorder transition. If this narrow stability is unavoidable, it would severely limit applications. Here we present the discovery that applying just moderate pressure on Cu2OSeO3 substantially increases the absolute size of the skyrmion pocket. This insight demonstrates directly that tuning the electronic structure can lead to a significant enhancement of the skyrmion lattice stability. We interpret the discovery by extending the previously employed Ginzburg-Landau approach and conclude that change in the anisotropy is the main driver for control of the size of the skyrmion pocket. This realization provides an important guide for tuning the properties of future skyrmion hosting materials., Comment: submitted to Scientific Reports

We present a detailed study of the phase diagram surrounding the skyrmion lattice (SkL) phase of Cu2OSe2O3 using high-precision magnetic ac susceptibility measurements. An extensive investigation of transition dynamics around the SkL phase using the imaginary component of the susceptibility revealed that at the conical-to-SkL transition a broad dissipation region exists with a complex frequency dependence. The analysis of the observed behavior within the SkL phase indicates a distribution of relaxation times intrinsically related to SkL. At the SkL-to-paramagnet transition a narrow first-order peak is found that exhibits a strong frequency and magnetic field dependence. Surprisingly, very similar dependence has been discovered for the first-order transition below the SkL phase, i.e. where the system enters the helical and conical state(s), indicating similar processes across the order-disorder transition., Comment: Accepted for publication in PRB

Uniquely in Cu2OSeO3, the Skyrmions, which are topologically protected magnetic spin vortex-like objects, display a magnetoelectric coupling and can be manipulated by externally applied electric (E) fields. Here, we explore the E-field coupling to the magnetoelectric Skyrmion lattice phase, and study the response using neutron scattering. Giant E-field induced rotations of the Skyrmion lattice are achieved that span a range of $\sim$25$^{\circ}$. Supporting calculations show that an E-field-induced Skyrmion distortion lies behind the lattice rotation. Overall, we present a new approach to Skyrmion control that makes no use of spin-transfer torques due to currents of either electrons or magnons., Comment: 5 pages, 3 figures

We present a detailed AC susceptibility investigation of the fluctuation regime in the insulating cubic helimagnet Cu2OSeO3. For magnetic fields mu_0 H >= 200 mT, and over a wide temperature range, the system behaves according to the scaling relations characteristic of the classical 3D Heisenberg model. For lower magnetic fields the scaling is preserved only at higher T, and becomes renormalized in a narrow T range above the transition temperature. Contrary to the well-studied case of MnSi, where the renormalization has been interpreted within the Brazovskii theory, our analysis of the renormalization at H = 0 shows the fluctuation regime in Cu2OSeO3 to lie closer to that expected within the Wilson-Fischer scenario., Comment: accepted for publication in PRB Rapid

Using SQUID magnetometry techniques, we have studied the change in magnetization versus applied ac electric field, i.e. the magnetoelectric (ME) susceptibility dM/dE, in the chiral-lattice ME insulator Cu2OSeO3. Measurements of the dM/dE response provide a sensitive and efficient probe of the magnetic phase diagram, and we observe clearly distinct responses for the different magnetic phases, including the skyrmion lattice phase. By combining our results with theoretical calculation, we estimate quantitatively the ME coupling strength as {\lambda} = 0.0146 meV/(V/nm) in the conical phase. Our study demonstrates the ME susceptibility to be a powerful, sensitive and efficient technique for both characterizing and discovering new multiferroic materials and phases., Comment: 14 pages, 4 figures

We present the experimental phase diagram of LiHo$_x$Er$_{1-x}$F$_4$, a dilution series of dipolar-coupled model magnets.The phase diagram was determined using a combination of AC susceptibility and neutron scattering. Three unique phases in addition to the Ising ferromagnet LiHoF$_4$ and the XY anti-ferromagnet LiErF$_4$ have been identified. Below $x=0.86$ an embedded spin-glass phase is observed, where a spin-glass exists within the ferromagnetic structure. Below $x=0.57$ an Ising spin-glass is observed consisting of frozen needle-like clusters. For $x \sim 0.3 - 0.1$ an antiferromagnetically coupled spin-glass occurs. A reduction of $T_C(x)$ for the ferromagnet is observed which disobeys the mean-field predictions that worked for LiHo$_x$Y$_{1-x}$F$_4$., Comment: 11 pages, 5 figures

We present the investigation of a monoclinic compound SeCuO3 using x-ray powder diffraction, magnetization, torque and electron-spin-resonance (ESR). Structurally based analysis suggests that SeCuO3 can be considered as a 3D network of tetramers. The values of intra-tetramer exchange interactions are extracted from the temperature dependence of the susceptibility and amount to ~200 K. The inter-tetramer coupling leads to the development of long-range antiferromagnetic order at TN = 8 K. An unusual temperature dependence of the effective g-tensors is observed, accompanied with a rotation of macroscopic magnetic axes. We explain this unique observation as due to site-selective quantum correlations.

Small-angle neutron scattering has been employed to study the influence of applied electric (E-) fields on the skyrmion lattice in the chiral lattice magnetoelectric Cu2OSeO3. In an experimental geometry with the E-field parallel to the [111] axis, and the magnetic field parallel to the [1-10] axis, we demonstrate that the effect of applying an E-field is to controllably rotate the skyrmion lattice around the magnetic field axis. Our results are an important first demonstration for a microscopic coupling between applied E-fields and the skyrmions in an insulator, and show that the general emergent properties of skyrmions may be tailored according to the properties of the host system., Comment: 12 pages, 4 figures, published version (including final proof corrections). Article is free to download at http://iopscience.iop.org/0953-8984/24/43/432201/

We report a detailed single crystal investigation of a magnetoelectric ferrimagnet Cu2OSeO3 using dc magnetization and ac susceptibility along the three principal directions [100], [110] and [111]. We have observed that in small magnetic fields two magnetic transitions occur, one at Tc = 57 K and the second one at TN = 58 K. At Tc the non-linear susceptibility reveals the emergence of the ferromagnetic component and below Tc the magnetization measurements show the splitting between field-cooled and zero-field-cooled regimes. Above 1000 Oe the magnetization saturates and the system is in a single domain state. The temperature dependence of the saturation below Tc can be well described by m(T) = m(0)[1 - (T/Tc)^2]^{\beta}, with m(0) = 0.56 (mu)B/Cu, corresponding to the 3-up-1-down configuration. The dielectric constant measured on a thin single crystal shows a systematic deviation below the transition, indicating an intrinsic magnetoelectric effect., Comment: accepted for publication in PRB

Magnetic dynamics of a bulk ferromagnet, a new single crystalline compound Co7(TeO3)4Br6, was studied by ac susceptibility and the related techniques. Very large Arrhenius activation energy of 17.2 meV (201 K) and long attempt time (2x10^(-4)s) span the full spectrum of magnetic dynamics inside a convenient frequency window, offering a rare opportunity for general studies of magnetic dynamics. Within the experimental window the ac susceptibility data build almost ideally semicircular Cole-Cole plots. Comprehensive study of experimental dynamic hysteresis loops of the compound is presented and interpreted within a simple thermal-activation-assisted spin lattice relaxation model for spin reversal. Quantitative agreement between the experimental results and the model's prediction for dynamic coercive field is achieved by assuming the central physical quantity, the Debye relaxation rate, to depend on frequency, as well as on the applied field strength and sample temperature. Cross-over between minor- to major hysteresis loops is carefully analyzed. Low-frequency limitations of the model, relying on domain wall pinning effects, are experimentally detected and appropriately discussed., Comment: A paragraph on dynamical-hysteresis assymetry added, text partially revised; Accepted in Physical Review B

We report a comprehensive study of magnetic properties of Ni3TeO6. The system crystallizes in a noncentrosymmetric rhombohedral lattice, space group R3. There are three differently coordinated Ni atoms in the unit cell. Two of them form an almost planar honeycomb lattice, while the third one is placed between the layers. Magnetization and specific heat measurements revealed a single magnetic ordering at TN = 52 K. Below TN the susceptibility with the magnetic field parallel to the c-axis drops towards zero while the perpendicular susceptibility remains constant, a characteristic of antiferromagnetic materials. Neutron diffraction confirmed that the system is antiferromagnet below TN with ferromagnetic ab-planes stacked antiferromagnetically along the c-axis. All Ni moments are in the S = 1 spin state and point along the c-axis., Comment: accepted for publication in Journal of Physics Condensed Matter

Pronounced anisotropy of magnetic properties and complex magnetic order of a new oxi-halide compound Co7(TeO3)4Br6 has been investigated by powder and single crystal neutron diffraction, magnetization and ac susceptibility techniques. Anisotropy of susceptibility extends far into the paramagnetic temperature range. A principal source of anisotropy are anisotropic properties of the involved octahedrally coordinated single Co(2+) ions, as confirmed by angular-overlap-model calculations presented in this work. Incommensurate antiferromagnetic order sets in at TN=34 K. Propagation vector is strongly temperature dependent reaching k1=(0.9458(6), 0, 0.6026(5)) at 30 K. A transition to a ferrimagnetic structure with k2=0 takes place at TC=27 K. Magnetically ordered phase is characterized by very unusual anisotropy as well: while M-H scans along b-axis reveals spectacularly rectangular but otherwise standard ferromagnetic hysteresis loops, M-H studies along other two principal axes are perfectly reversible, revealing very sharp spin flop (or spin flip) transitions, like in a standard antiferromagnet (or metamagnet). Altogether, the observed magnetic phenomenology is interpreted as an evidence of competing magnetic interactions permeating the system, first of all of the single ion anisotropy energy and the exchange interactions. Different coordinations of the Co(2+)-ions involved in the low-symmetry C2/c structure of Co7(TeO3)4Br6 render the exchange-interaction network very complex by itself. Temperature dependent changes in the magnetic structure, together with an abrupt emergence of a ferromagnetic component, are ascribed to continual spin reorientations described by a multi-component, but yet unknown, spin Hamiltonian., Comment: 12 pages, 13 figures; submitted to PRB

We have performed an investigation of the nonlinear magnetic response in ruthenocuprates. A negative, diverging-like peak at the main magnetic transition T_N in RuSr2RECu2O8 (RE = Gd, Y) indicates a possible canted antiferromagnetic order. Another well defined feature above T_N points to a blocking of superparamagnetic particles through the T^(-3) dependence of the third harmonic at higher temperatures. Below T_N a nondiverging peak appears, which is strongly affected by the addition of 10% of Cu ions in the RuO2 planes. In RuSr2RE(2-x)Ce(x)Cu2O10 the main magnetic transition T_M is accompanied by two characteristic temperatures in the third harmonic of the ac susceptibility, in agreement with recent studies from uSR and Mossbauer spectroscopy. We find that the spin-spin correlation temperature is the same in both families of ruthenocuprates., Comment: accepted for publication in EPJB

A new magnetic transition in the ruthenocuprate parent compound RuSr2EuCeCu2O10 has been observed below 10 K. It shows up only as a kink in the imaginary part of the ac susceptibility and exhibits a pronounced frequency dependence. At the same time, the real part of the ac susceptibility and the dc magnetization study show very little change in the same temperature window suggesting only a minor fraction of the material to be involved in the transition. Frequency dependence shows excellent agreement with the predictions of the Arrhenius law known to describe well the dynamics of the superparamagnetic particles. The same type of the investigation on the RuSr2Eu1.1Ce0.9Cu2O10 composition showed no evidence of the similar transition, which points to a possible intrinsic behavior., Comment: to be published in Physica C

We report detailed studies of the ac susceptibility butterfly hysteresis on the Ru1222 ruthenocuprate compounds. Two separate contributions to these hysteresis have been identified and studied. One contribution is ferromagnetic-like and is characterized by the coercive field maximum. Another contribution, represented by the so called inverted maximum, is related to the unusual inverted loops, unique feature of Ru1222 butterfly hysteresis. The different nature of the two identified magnetic contributions is proved by the different temperature dependences involved. By lowering the temperature the inverted peak gradually disappears while the coercive field slowly raises. If the maximum dc field for the hysteresis is increased, the size of the inverted part of the butterfly hysteresis monotonously grows while the position of the peak saturates. In reaching saturation exponential field dependence has been demonstrated to take place. At T = 78 K the saturation field is 42 Oe., Comment: 5 pages, 5 figures

We report on magnetic properties of cubic compound Cu3TeO6 studied by $ac$ and $dc$ susceptibility and neutron powder diffraction for the first time. A novel magnetic lattice, three dimensional spin web, composed of almost planar regular hexagons of Cu2+, S =1/2 spins, defines the properties of Cu3TeO6. The behavior of the magnetic susceptibility in the paramagnetic state at approximately 170 K is suggestive for a competition between local anisotropies of Cu2+ hexagons. The resulting frustration is weaker than the antiferromagnetic nearest-neighbor interaction which leads to a collinear (or slightly canted) spin arrangement (k=0,0,0) and formation of magnetic domains below TN=61 K., Comment: Submitted to PRL

High-resolution ac susceptibility and thermal conductivity measurement on Cu2Te2O5X2(X=Br,Cl) single crystals are reported. For Br-sample, sample dependence prevents to distinguish between possibilities of magnetically ordered and spin-singlet ground states. In Cl-sample a three-dimensional transition at 18.5 K is accompanied by almost isotropic behavior of susceptibility and almost switching behavior of thermal conductivity. Thermal conductivity studies suggest the presence of a tremendous spin-lattice coupling characterizing Cl- but not Br-sample. Below the transition Cl-sample is in a complex magnetic state involving AF order but also the elements consistent with the presence of a gap in the excitation spectrum., Comment: version accepted for publication in Phys.Rev.B-Rapid Communication

We report ac susceptibility data on RuSr_2(Eu,Ce)_2Cu_2O_(10-y) (Ru-1222, Ce content x=0.5 and 1.0), RuSr_2GdCu_2O_8 (Ru-1212) and SrRuO_3. Both Ru-1222 (x=0.5, 1.0) sample types exhibit unexpected magnetic dynamics in low magnetic fields: logarithmic time relaxation, switching behavior, and `inverted' hysteresis loops. Neither Ru-1212 nor SrRuO_3 exhibit such magnetic dynamics. The results are interpreted as evidence of the complex magnetic order in Ru-1222. We propose a specific multilayer model to explain the data, and note that superconductivity in the ruthenocuprate is compatible with both the presence and absence of the magnetic dynamics., Comment: 9 pages, 11 figures, Revtex; submitted to Phys.Rev.B

We report ac susceptibility measurements on polycrystalline samples of SrRuO_3 and three ruthenocuprates: superconducting RuSr_2GdCu_2O_8 (Ru-1212), superconducting RuSr_2Eu_(2-x)Ce_xCu_2O_y (Ru-1222, x=0.5) and nonsuperconducting, insulating RuSr_2Eu_(2-x)Ce_xCu_2O_z (Ru-1222, x=1.0). Ac susceptibility of both Ru-1222 compositions exhibit logarithmic time relaxation and `inverted' hysteresis loops. Ru-1212 samples exhibit none of these behaviors. We interpret the magnetic behavior of Ru-1222 in the framework of weakly coupled magnetic multilayers and argue that superconductivity coexists with qualitatively different magnetic behaviors., Comment: 4 pages, 4 figures; submitted to Phys.Rev.Lett. Some technical errors corrected