Low-temperature Magnetic Transition Research Articles

Tunable magnetic order in low-symmetry SeO3 ligand linked TM3(SeO3)3H2O ( TM=Mn , Co, and Ni) compounds

Generally, one has two strategies to achieve magnetic frustration: through geometric means or interactions with different length scales. As the former leads to much simpler theoretical treatments it is favored and so magnetic sublattices with geometric frustration are sought after. One approach to finding such lattices is to design them chemically by using non-magnetic linker ligands. Here we report on the magnetic properties of one such family of materials, the transition metal ($TM$) selenite hydrate compounds chemical formula $TM_3$(SeO$_3$)$_3$H$_2$O . These materials link highly distorted $TM$O$_6$ octahedra via non-magnetic [SeO$_3$]$^{2+}$ linkers. Using $TM$ = Mn, Co and Ni we report on the structural effects of changing the $TM$ site and how they may influence the magnetic structure. Using magnetic susceptibility and neutron powder diffraction we identify low temperature magnetic transitions for all three compounds characterized by the onset of long-range AFM order with moderate frustration indexes. Consideration of the magnetic structures reveal that the magnetic order is sensitive to the $TM$ site ion and is tunable as it is changed - especially from Mn to Co - with changes in both the moment direction and the ordering vector. Field dependent susceptibility and heat capacity measurements reveal metamagnetic transitions in both Mn$_3$(SeO$_3$)$_3$H$_2$O and Co$_3$(SeO$_3$)$_3$H$_2$O indicating nearby magnetic ground states accessible under relatively small applied fields. Density functional theory calculations broadly confirm these results, showing both a sensitivity of the magnetic structure to the $TM$ and its local environment. Although no spin liquid behavior is achieved, these results suggest the fruitfulness of such synthesis philosophies and encourage future work to engender higher frustration in these materials via doping, field, pressure or larger linker ligands.

Effect of Mn-doping on the low temperature magnetic phase transitions of BiFeO3

In the present work, we have carried out a comparative study of the low temperature phase transitions using dc magnetization (M (T)) and ac susceptibility (χ (ω, T)) measurements on undoped and 0.3 wt% MnO2 doped BiFeO3 samples in the 2–300 K temperature range. It is shown that MnO2 doping increases the resistivity and decreases the dielectric loss as a result of reduced oxygen vacancy concentration as confirmed by iodometry and x-ray photoelectron spectroscopy (XPS) studies. A comparative study of the dc M (T) and ac χ (ω, T) results on two types of samples reveal that the transitions around 25 K, 110 to 150 K and 260 K are intrinsic to BiFeO3. The widely reported transition at 50 K is argued to be defect induced, as it is absent in the doped samples. We also show that the spin-glass transition temperature (TSG) ∼20 K, determined from an analysis of χ (ω, T), is less than the spin-glass freezing temperature (Tf) ∼25 K in marked contrast to TSG > Tf reported by earlier workers.

Lattice disorder effect on magnetic ordering of iron arsenides

This study investigates magnetic ordering temperature in nano- and mesoscale structural features in an iron arsenide. Although magnetic ground states in quantum materials can be theoretically predicted from known crystal structures and chemical compositions, the ordering temperature is harder to pinpoint due to potential local lattice variations that calculations may not account for. In this work we find surprisingly that a locally disordered material can exhibit a significantly larger Néel temperature (TN) than an ordered material of precisely the same chemical stoichiometry. Here, a EuFe2As2 crystal, which is a ‘122’ parent of iron arsenide superconductors, is found through synthesis to have ordering below TN = 195 K (for the locally disordered crystal) or TN = 175 K (for the ordered crystal). In the higher TN crystals, there are shorter planar Fe-Fe bonds [2.7692(2) Å vs. 2.7745(3) Å], a randomized in-plane defect structure, and diffuse scattering along the [00 L] crystallographic direction that manifests as a rather broad specific heat peak. For the lower TN crystals, the a-lattice parameter is larger and the in-plane microscopic structure shows defect ordering along the antiphase boundaries, giving a larger TN and a higher superconducting temperature (Tc) upon the application of pressure. First-principles calculations find a strong interaction between c-axis strain and interlayer magnetic coupling, but little impact of planar strain on the magnetic order. Neutron single-crystal diffraction shows that the low-temperature magnetic phase transition due to localized Eu moments is not lattice or disorder sensitive, unlike the higher-temperature Fe sublattice ordering. This study demonstrates a higher magnetic ordering point arising from local disorder in 122.

Thermodynamic Functions of Complex Zirconia Based Lanthanide Oxides—Pyrochlores Ln2Zr2O7 (Ln = La, Pr, Sm, Eu, Gd) and Fluorites Ln2O3 · 2ZrO2 (Ln = Tb, Ho, Er, Tm)

The review of the thermodynamic properties of complex lanthanide–zirconium oxides, namely, Ln2Zr2O7 (Ln = La, Pr, Sm, Eu, Gd) with a pyrochlore structure and Ln2O3 · 2ZrO2 solid solutions (Ln = Tb, Ho, Er, Tm) with a fluorite structure, is presented on the basis of our and literature data. The heat capacity was experimentally studied for Ln2Zr2O7 (for the cerium subgroup lanthanides) with a pyrochlore structure (Fd3m) and Ln2O3 · 2ZrO2 (for the yttrium subgroup lanthanides) with a fluorite structure (Fm3m), which were characterized by X-ray diffraction and elemental analyses, scanning electron microscopy, and adiabatic and differential scanning calorimetry. The temperature dependences of the thermodynamic functions (entropy, enthalpy change, and reduced Gibbs energy) were calculated within a broad range of temperatures from smoothed heat capacity values. The available thermodynamic data were compared, and some recommended values were given. The contribution of low-temperature magnetic transitions was taken into account for Ln2Zr2O7 (Ln = Pr, Nd, Sm, Gd). The effect of the Schottky anomaly on the heat capacity of lanthanide compounds was analyzed.

Characterization of LiFePO4 samples obtained by pulse combustion under various conditions of synthesis

Lithium iron phosphate (LiFePO4, LFP) is one of the widely used cathode materials for rechargeable lithium ion batteries. LFP batteries are widely used for electric vehicles and backup power due to their important advantages such as low cost, lifetime, efficiency, and reliability. There are still several technical challenges that need to be addressed: the increase of energy density or further reduction of their final cost. This paper concerned with the characterization of carbon coated LiFePO4 nanopowder cathode materials produced under different conditions by pulse combustion for providing energy to the reactor for the synthesis. The reactor was built according to the principles of the thermoacoustic burner on the basis of the Helmholtz resonator. The investigated nanopowders are synthesized by complete and incomplete combustion and calcined at 700 °C. The obtained samples were characterized by X-ray diffraction, Fourier transform infrared, Raman, and Mössbauer spectroscopy. Observed low-temperature magnetic phase transitions definitively identified the crystal phases. The morphology of samples was controlled by scanning electron microscopy. The aim of this work is to show that it is possible to achieve a desired crystal phase by pulse combustion in a relatively cheap and fast way. The extremely rapid synthesis of almost pure phase material is possible due to the reduction in size of interacting particles and to an enormous number of collisions between them as a result of strong turbulent flow associated with explosive combustion.

Negative Magnetic Entropy Change and Critical Behavior of Manganite La0.8Sr0.2Mn1−xCoxO3 (x = 0, 0.2)

La0.8Sr0.2Mn1−xCoxO3 (x = 0, 0.2) polycrystalline samples were prepared by solid-state reaction, and their structural, Griffiths phase, magnetic entropy change, critical behavior, and electrical transport properties were systematically investigated. The results show that all polycrystalline samples are rhombohedral symmetry structures; the Griffiths phase exists above the low-temperature magnetic transition temperature (TC2) of the two samples; the magnetic field is applied to the La0.8Sr0.2Mn1−xCoxO3 (x = 0, 0.2) samples. The maximum magnetic entropy change ΔSmax for 7 T is − 2.28 and − 2.36 J/(kg K), respectively. The doping of Co makes ΔSmax increase, and an obvious negative entropy change occurs at low temperature and low field; the critical behavior of La0.8Sr0.2MnO3 (LSMO) fits best with the mean field model, and the critical behavior of the sample after doping with the 3D Heisenberg model fits best; LSMO is a semiconductor material, and the metal insulator transition appears near the low-temperature magnetic transition temperature (TC2) when the Co element doping amount reaches 0.2. The conductivity of the two samples in the high-temperature region satisfies the small polaron model.

Low-temperature magnetic transitions in Fe2MnSi Heusler alloys prepared in bulk and ribbon form

Abstract Microstructural and magnetic properties of the Fe2MnSi Heusler alloys in the bulk and ribbon form have been investigated from a viewpoint of technology of their production. The bulk alloys were prepared by arc and induction melting while for the ribbon-type samples the planar flow casting technology was used. X-ray diffraction has confirmed a presence of the L21 cubic phase in both polished 500 µm thick discs cut from a button and cylinder type ingots of the same chemical composition and in the 20 μm thick and 2 mm wide ribbon. Values of lattice parameters (0.560–0.571 nm) obtained for discs and both ribbon sides were almost independent on technology, which, on the other hand, has markedly influenced the microstructure yielding the large size of grains and grain boundaries in the disc samples in comparison to about two orders of magnitude smaller grains in the ribbon sample. From the magnetic viewpoint all alloys were paramagnetic at a room temperature contrary to their magnetic behaviour at low temperatures. The slight excess of Mn at the expense of Fe in the chemical composition of the ribbon sample detected by the energy dispersive X-ray spectroscopy has contributed to a marked positive shift of the Curie temperature (Tc ≈ 270 K and 215–230 K for ribbon and bulk samples, respectively). The second magnetic transition of a magnetic moment re-orientation observed at about 69 K was similar for all kinds of samples.

Crystallographic and magnetic investigations of textured bismuth ferrite lead titanate layers

— In present work we demonstrate the synthesis of textured 60BiFeO3–40PbTiO3 (60:40 BFPT) by using the templated grain growth technique with platelets of BaTiO3. Synthesised 60:40 BFPT has been examined by High-energy x-ray diffraction utilizing a synchrotron x-ray source. The crystallographic structure refinement results revealed the co-existence of monoclinic and tetragonal phases. By employing an external electric field, the mixed monoclinic/tetragonal phases transformed to the predominantly tetragonal phase. In addition, a crystallographic texture refinement was completed on unpoled state of 60:40 BFPT which showed the sample had 1.3 multiples of random distribution (MRD) crystallographic textured in tetragonal phase. However, magnetic measurements showed isotropic ferromagnetism for the sample which is not in agreement with the crystallographic texture properties of the sample. Low temperature magnetic transition has been found in zero field cooled—field cooled (ZFC-FC) measurements. This could be due to the possible existence of a secondary magnetic phase, which dominated the magnetic result.

Investigation of the crystal structure and cryogenic magnetic properties of RE2T2Al (RE = Dy, Ho, Er, and Tm; T = Co and Ni) compounds

The crystal structure, and cryogenic magnetic and magnetocaloric properties in RE2T2Al (RE = Dy, Ho, Er, and Tm; T = Co and Ni) compounds have been investigated. All the compounds belong to an orthorhombic W2B2Co-type structure (Immm space group). A second order paramagnetic to ferromagnetic phase transition exists for RE2Co2Al compounds at TC = 62, 27, 32, and 11.5 K, whereas the compounds of RE2Ni2Al undergo a paramagnetic to antiferromagnetic phase transition with the Néel temperatures (TN) of 19, 12, 12.5, and 6 K for RE = Dy, Ho, Er, and Tm, respectively. Moreover, an additional low temperature magnetic transition occurs for all present RE2T2Al compounds. An obvious hysteresis was observed at a low temperature in the Dy2Co2Al, Ho2Co2Al, and Er2Co2Al compounds. The values of the maximum magnetic entropy change (−ΔSMmax) are 10.4, 11.5, 5.9, 7.7, 6.0, and 16.2 J/kg K for Dy2Co2Al, Ho2Co2Al, Er2Co2Al, Tm2Co2Al, Ho2Ni2Al, and Er2Ni2Al compounds with a field change (ΔH) of 0-5 T, respectively. Moreover, two peaks (or shoulder) in the −ΔSM (T) curves of Ho2Co2Al can be observed, which lead to a wide cooling temperature interval.

Effect of oxygen pressure on structural and magnetic properties of Nd2NiMnO6 thin films grown on different substrates

Double perovskites have been studied extensively in the bulk form however very few reports are available on their thin films. Here we are presenting results on first time grew thin films of double perovskite Nd2NiMnO6 (NNMO). We report the comparative structural and magnetic studies of the PLD grown thin films on different substrates i.e. SrTiO3 (STO) and MgO. X-ray diffraction (XRD) profiles show that the film grown on STO is epitaxial whereas it is polycrystalline on MgO substrate. Films on both the substrates were grown at 800 mTorr and 200 mTorr oxygen partial pressure. We observe that the film shows the magnetic behavior similar to the bulk sample. We observe the high-temperature ferromagnetic transition near 192 K along with an additional transition observed in the low temperature region (vicinity of 100 K) in Field cooled (FC) magnetization. Super-exchange interaction between Ni2+-O-Mn4+ is attributed to the ferromagnetic ordering in these samples. Mixed valence states Ni3+ and Mn3+ present in the films leads to antiferromagnetic (AFM) interactions which attributes to the appearance of low temperature magnetic transition. The oxygen pressure applied while growing the thin films was found to affect the magnetic moment of NNMO films significantly.

The study of entropy change and magnetocaloric response in magnetic nanoparticles via heat capacity measurements

In our work, we have investigated the magnetocaloric effect (MCE) of core@shell Co@Au nanoparticles by heat capacity Cp measurement in temperature range 1.9–55 K under external magnetic field. After the subtraction of lattice heat capacity contribution, the maximum of isothermal magnetic entropy change ΔSm = 3.11 J K−1 kg−1 was obtained at field change from 0 to 9 T. Adiabatic temperature change ΔTad = 3.31 K, refrigerant capacity power RCP = 88.9 J kg−1 and efficiency of adiabatic temperature change η = 0.37 K/T at the same external magnetic field change were established for the investigated system. The comparison of the results to the independent magnetic measurements data revealed the accordance of fundamental magnetocaloric characteristics obtained by both methods. Thus, this work is also the first experimental confirmation of relation between magnetocaloric response of nanoparticles and the low temperature magnetic transition from superparamagnetic to blocking/freezing state.

Monte Carlo study of a geometrically frustrated rare-earth magnetic compound: SrGd2O4

We study the low-temperature magnetic phase transitions and phase diagram of one member of the lanthanide family of frustrated compounds, ${\text{SrGd}}_{2}{\text{O}}_{4}$, using Monte Carlo simulation techniques. A detailed experimental study of two members of the ${\text{SrLn}}_{2}{\text{O}}_{4}$ family of compounds, ${\text{SrHo}}_{2}{\text{O}}_{4}$ and ${\text{SrGd}}_{2}{\text{O}}_{4}$, has recently been carried out by Young et al. [O. Young, Ph.D. thesis, University of Warwick, 2013; O. Young, G. Balakrishnan, M. R. Lees, and O. A. Petrenko, Phys. Rev. B 90, 094421 (2014)]. A phase diagram for ${\text{SrGd}}_{2}{\text{O}}_{4}$ was mapped out in the field-temperature ($H\ensuremath{-}T$) plane from magnetization, susceptibility, and specific-heat measurements and several ordered phases were identified. However, the detailed nature of these phases was not determined. We have used a model of classical Heisenberg spins to investigate the low-temperature behavior. Our simulation results qualitatively agree with the experimental findings. By collecting data from all measured thermodynamic quantities, a $H\ensuremath{-}T$ phase diagram is constructed. It reveals four separate regions of phases with unique magnetic ordering. We have identified the nature of the order in each of these phases.

Exchange bias and spin glass transition in quaternary MnCuNiSn Heusler alloy

We have systematically investigated the exchange bias (EB) effect and low-temperature magnetic state transition in Mn42Cu6Ni42Sn10 Heusler alloy by means of AC and DC magnetization measurements. Experimental results suggest that the martensitic phase is in the state of superparamagnetic (SPM), following that the particles turn into the ferromagnetic (FM) state at the martensitic Curie temperature, and the moments are frozen as the temperature is below 150K. In addition, EB effect was observed in the phase separated martensitic state, which can achieves about 536Oe under the field of 500Oe after field-cooled (FC) to 10K. First-principle investigations indicate that such a small value is originated from nonmagnetic Cu atoms substitution. The appearance of EB effect can be ascribed to the competition between the FM martensitic phase and spin glass (SG) phase due to the impact of Mn atoms, whereas the nonmagnetic Cu atoms doping would hinder the magnetic aggregation, resulting the small EB value eventually.

Magnetic, ferroelectric, and spin phonon coupling studies of Sr3Co2Fe24O41 multiferroic Z-type hexaferrite

The magnetic, Raman, ferroelectric, and in-field 57Fe Mössbauer studies of polycrystalline multiferroic Sr3Co2Fe24O41 are reported in this paper. From the magnetization studies, it is observed that the sample is soft magnetic in nature with low temperature magnetic spin transitions like longitudinal to transverse conical structure around 130 K and change in magnetic crystalline anisotropy from conical to planar structure at 250 K. Ferroelectric studies of the sample exhibit the spontaneous polarization at low temperature. Strong spin phonon and spin lattice coupling is observed through low temperature Raman spectroscopy. From the in-field 57Fe Mössbauer spectroscopy, spin up and spin down site occupations of Fe ions are calculated in the unit cell.

Polaronic charge transfer and large dielectric constant inCa3CoRhO6

We report the dc electrical conductivity and ac impedance study of the spin chain compound CaCoRhO. The sample shows a variable range hopping-assisted dc conduction below 250 K, while a nearest neighbor small polaron hopping is observed at higher temperatures. A reasonably large frequency-independent ac dielectric permittivity (3200) is observed around room temperature. The activation energy associated with the relaxation peaks in loss tangent below 200 K is found to be close to the variable range hopping energy of the dc resistivity data which signifies the active role of the charge carrier hopping toward the ac dielectric data. The characteristic time constant associated with the relaxation (7.2 × 10−11 s) and the value of activation energy (116 meV) suggest a polaronic charge transfer in the system. The modulus analysis suggests that the relaxation in permittivity is due to the intrinsic grain effect and it is likely to be associated with charge transfer between transition metal ions in a system where their mixed valence nature is already reported. The sample also shows dielectric anomaly close to the low-temperature magnetic transition, although we failed to observe any ground state spontaneous electric polarization.

Low-temperature magnetic phase transitions in the multiferroic Nd0.9Dy0.1Fe3(BO3)4. Part 1. Transitions induced by magnetic fields directed along the trigonal symmetry axis. Spontaneous transitions with temperature changes

The elastic and magnetic characteristics of single-crystal Nd0.9Dy0.1Fe3(BO3)4 are studied at low temperatures in zero magnetic field and in external fields H||C3. The temperature dependences of the acoustic mode velocities and the magnetic susceptibility manifest a transition of the magnetic subsystem into a magnetically ordered state and two successive, spontaneous spin-reorientation phase transitions. The possibility of a spontaneous transition into an incommensurate (spiral) magnetic phase in the crystal is discussed. It is shown that an external magnetic field directed along the trigonal axis of the crystal induces a sequence of spin-reorientation phase transitions. An H-T phase diagram (H||C3) is constructed for this compound.

Variable defect structures cause the magnetic low-temperature transition in natural monoclinic pyrrhotite

Non-stoichiometric monoclinic 4C pyrrhotite (Fe7S8) is a major magnetic remanence carrier in the Earth's crust and in extraterrestrial materials. Because of its low-temperature magnetic transition around 30 K also known as Besnus transition, which is considered to be an intrinsic property, this mineral phase is easily detectable in natural samples. Although the physical properties of pyrrhotite have intensively been studied, the mechanism behind the pronounced change in magnetization at the low-temperature transition is still debated. Here we report magnetization experiments on a pyrrhotite crystal (Fe6.6S8) that consists of a 4C and an incommensurate 5C* superstructure that are different in their defect structure. The occurrence of two superstructures is magnetically confirmed by symmetric inflection points in hysteresis measurements above the transition at about 30 K. The disappearance of the inflection points and the associated change of the hysteresis parameters indicate that the two superstructures become strongly coupled to form a unitary magnetic anisotropy system at the transition. From this it follows that the Besnus transition in monoclinic pyrrhotite is an extrinsic magnetic phenomenon with respect to the 4C superstructure and therefore the physics behind it is in fact different from that of the well-known Verwey transition.

Electronic transport properties of MFe2As2 (M = Ca, Eu, Sr) at ambient and high pressures up to 20 GPa

We experimentally investigated the electronic transport properties of four iron pnictide crystals, namely, EuFe2As2, SrFe2As2, and CaFe2As2 parent compounds, and superconducting CaFe1.94Co0.06As2 at ambient and high pressures up to 20 GPa. At ambient pressure we examined the electrical resistivity, Hall and magnetoresistance effects of the samples in a temperature range from 1.5 to 380 K in high magnetic fields up to 13.6 T. In this work we carried out the first simultaneous investigations of the in-plane and out-of-plane Hall coefficients, and found new peculiarities of the low-temperature magnetic and structural transitions that occur in these materials. In addition, the Hall coefficient data suggested that the parent compounds are semimetals with a multi-band conductivity that includes hole-type and electron-type bands. We measured the pressure dependence of the thermoelectric power (the Seebeck effect) of these samples up to 20 GPa, i.e. across the known phase transition from the tetragonal to the collapsed tetragonal lattice. The high-pressure behavior of the thermopower of EuFe2As2 and CaFe2As2 showing the p-n sign inversions was consistent with the semimetal model described above. By means of thermopower, we found in single-crystalline CaFe2As2 direct evidence of the band structure crossover related to the formation of As–As bonds along the c-axis on the tetragonal → collapsed tetragonal phase transition near 2 GPa. We showed that this feature is distinctly observable only in high-quality samples, and already for re-pressurization cycles this crossover was strongly smeared because of the moderate deterioration of the sample. We also demonstrated by means of thermopower that the band structure crossover that should accompany the tetragonal → collapsed tetragonal phase transition in EuFe2As2 near 8 GPa is hardly visible even in high-quality single crystals. This behavior may be related to a gradual valence change of the Eu ions under pressure that leads to an injection of free electrons and the steady shift of the conduction to n-type.

Competing magnetic interactions and low temperature magnetic phase transitions in composite multiferroics

Novel magnetic properties and magnetic interactions in composite multiferroic oxides Pb[(Zr0.52Ti0.48)0.60(Fe0.67W0.33).40]O3]0.80–[CoFe2O4]0.20 (PZTFW–CFO) have been studied from 50 to 1000 Oe field cooled (FC) and zero field cooled (ZFC) probing conditions, and over a wide range of temperatures (4–350 K). Crystal structure analysis, surface morphology, and high resolution transmission electron microscopy images revealed the presence of two distinct phases, where micro- and nano-size spinel CFO were embedded in tetragonal PZTFW matrix and applied a significant built-in compressive strain (∼0.4–0.8%). Three distinct magnetic phase transitions were observed with the subtle effect of CFO magnetic phase on PZTFW magnetic phase transitions below the blocking temperature (TB). Temperature dependence magnetic property m(T) shows a clear evidence of spin freezing in magnetic order with lowering in thermal vibration. Chemical inhomogeneity and confinement of nanoscale ferrimagnetic phase in paramagnetic/antiferromagnetic matrix restrict the long range interaction of spin which in turn develop a giant spin frustration. A large divergence in the FC and ZFC data and broad hump in ZFC data near 200 (±10) K were observed which suggests that large magnetic anisotropy and short range order magnetic dipoles lead to the development of superparamagnetic states in composite.

Low-temperature properties of theS=12spin systemYb3Ru4Al12with a distorted kagome lattice structure

We have synthesized single crystals of ternary intermetallic ${\mathrm{Yb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ with a distorted kagome lattice structure, and investigated the low-temperature resistivity, specific heat, magnetization, and magnetic phase transitions. ${\mathrm{Yb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ is the first $4f$ system that has a ${\mathrm{Gd}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$-type crystal structure where antiferromagnetic interaction acts on the spin. The crystal electric field (CEF) ground state of this compound is determined as a well isolated twofold degenerate state that is subjected to a strong easy-plane-type magnetic anisotropy. In the present study, the spin system of ${\mathrm{Yb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ is regarded as an AFM $XY$ model of $S=1/2$. This compound undergoes successive magnetic phase transitions at 1.5 and 1.6 K, and the resistivity exhibits ${T}^{2}$ behavior below 1 K. The ratio of the coefficient of the ${T}^{2}$ term in the resistivity $A$, and that of the electronic specific heat coefficient ${\ensuremath{\gamma}}_{0}$, deviates from the Kadowaki-Woods (KW) law. The successive phase transitions and low-temperature properties of ${\mathrm{Yb}}_{3}{\mathrm{Ru}}_{4}{\mathrm{Al}}_{12}$ where geometrical frustration and heavy fermion behavior occur are discussed.