The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shigeki Onoda - One of the best experts on this subject based on the ideXlab platform.
-
roles of easy plane and easy axis xxz anisotropy and bond alternation in a frustrated ferromagnetic Spin 12 chain
Physical Review B, 2020Co-Authors: Hiroshi Ueda, Shigeki OnodaAbstract:The Spin-$1/2$ Heisenberg chain with a ferromagnetic first-neighbor exchange coupling $J_1$ and an antiferromagnetic second-neighbor $J_2$ has a Haldane dimer ground state with an extremely small Spin Gap. Thus, the ground state is readily altered by perturbations. Here, we investigate the effects of XXZ exchange magnetic anisotropy of both the easy-axis and easy-plane types and an alternation in $J_1$ on the ground state, the Spin Gap, and magnetic properties of the frustrated ferromagnetic Spin-$1/2$ chain. It is found that there are two distinct dimerized Spin-Gap phases, in one of which the Spin Gap and the magnetic susceptibility are extremely small around the SU(2) symmetric case and in the other they are moderately large far away from the SU(2) symmetric case. A small alternation in the amplitude of $J_1$ rapidly shortens the pitch of Spin correlations towards the four-Spin periodicity, as in the limit of $J_1/J_2\to0$. These effects are not sufficient to quantitatively explain overall experimentally observed magnetic properties in the quasi-one-dimensional Spin-Gapped magnetoelectric cuprate Rb$_2$Cu$_2$Mo$_3$O$_{12}$ that exhibits ferroelectricity stabilized by a magnetic field. Our results are also relevant to Cs$_2$Cu$_2$Mo$_3$O$_{12}$, where the ferromagnetic intrachain and antiferromagnetic interchain order has recently been found, in a single chain level. We also reveal the nature of symmetry-protected topological phase transitions in the model by mapping onto effective Spin-1 chain models.
-
roles of easy plane and easy axis xxz anisotropy and bond alternation in a frustrated ferromagnetic Spin 1 2 chain
Physical Review B, 2020Co-Authors: Hiroshi Ueda, Shigeki OnodaAbstract:The Spin-$1/2$ Heisenberg chain with a ferromagnetic first-neighbor exchange coupling ${J}_{1}$ and an antiferromagnetic second-neighbor ${J}_{2}$ has a Haldane dimer ground state with an extremely small Spin Gap. Thus the ground state is readily altered by perturbations. Here, we investigate the effects of XXZ exchange magnetic anisotropy of both the easy-axis and easy-plane types and an alternation in ${J}_{1}$ on the ground state, the Spin Gap, and magnetic properties of the frustrated ferromagnetic Spin-$1/2$ chain. It is found that there are two distinct dimerized Spin-Gap phases, in one of which the Spin Gap and the magnetic susceptibility are extremely small around the SU(2) symmetric case and in the other they are moderately large far away from the SU(2) symmetric case. A small alternation in the amplitude of ${J}_{1}$ rapidly shortens the pitch of Spin correlations towards the four-Spin periodicity, as in the limit of ${J}_{1}/{J}_{2}\ensuremath{\rightarrow}0$. These effects are not sufficient to quantitatively explain overall experimentally observed magnetic properties in the quasi-one-dimensional Spin-Gapped magnetoelectric cuprate ${\mathrm{Rb}}_{2}{\mathrm{Cu}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$ that exhibits ferroelectricity stabilized by a magnetic field. Our results are also relevant to ${\mathrm{Cs}}_{2}{\mathrm{Cu}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$, where the ferromagnetic intrachain and antiferromagnetic interchain order has recently been found, in a single chain level. We also reveal the nature of symmetry-protected topological phase transitions in the model by mapping onto effective Spin-1 chain models.
-
emergent Spin 1 haldane Gap and ferroelectricity in a frustrated Spin 1 2 ladder
Physical Review B, 2020Co-Authors: Hiroshi Ueda, Shigeki Onoda, Yasutaka Yamaguchi, Tsuyoshi Kimura, Daichi Yoshizawa, T Morioka, Masayuki Hagiwara, Masato Hagihala, Minoru Soda, Takatsugu MasudaAbstract:Combined experimental and theoretical studies reveal that the low-temperature magnetic properties of Rb${}_{2}$Cu${}_{2}$Mo${}_{3}$O${}_{12}$ are nicely explained in terms of a two-leg ladder of frustrated ferromagnetic Spin-$\frac{1}{2}$ chains. The system hosts a nonmagnetic tetramer ground state that is adiabatically connected to a couple of isolated Haldane dimer Spin-$\frac{1}{2}$ chains. Remarkably, ferroelectricity emerges at much lower magnetic fields than the Spin Gap, suggesting a rare case of ferroelectricity induced by vector Spin chirality.
Hiroshi Ueda - One of the best experts on this subject based on the ideXlab platform.
-
roles of easy plane and easy axis xxz anisotropy and bond alternation in a frustrated ferromagnetic Spin 12 chain
Physical Review B, 2020Co-Authors: Hiroshi Ueda, Shigeki OnodaAbstract:The Spin-$1/2$ Heisenberg chain with a ferromagnetic first-neighbor exchange coupling $J_1$ and an antiferromagnetic second-neighbor $J_2$ has a Haldane dimer ground state with an extremely small Spin Gap. Thus, the ground state is readily altered by perturbations. Here, we investigate the effects of XXZ exchange magnetic anisotropy of both the easy-axis and easy-plane types and an alternation in $J_1$ on the ground state, the Spin Gap, and magnetic properties of the frustrated ferromagnetic Spin-$1/2$ chain. It is found that there are two distinct dimerized Spin-Gap phases, in one of which the Spin Gap and the magnetic susceptibility are extremely small around the SU(2) symmetric case and in the other they are moderately large far away from the SU(2) symmetric case. A small alternation in the amplitude of $J_1$ rapidly shortens the pitch of Spin correlations towards the four-Spin periodicity, as in the limit of $J_1/J_2\to0$. These effects are not sufficient to quantitatively explain overall experimentally observed magnetic properties in the quasi-one-dimensional Spin-Gapped magnetoelectric cuprate Rb$_2$Cu$_2$Mo$_3$O$_{12}$ that exhibits ferroelectricity stabilized by a magnetic field. Our results are also relevant to Cs$_2$Cu$_2$Mo$_3$O$_{12}$, where the ferromagnetic intrachain and antiferromagnetic interchain order has recently been found, in a single chain level. We also reveal the nature of symmetry-protected topological phase transitions in the model by mapping onto effective Spin-1 chain models.
-
roles of easy plane and easy axis xxz anisotropy and bond alternation in a frustrated ferromagnetic Spin 1 2 chain
Physical Review B, 2020Co-Authors: Hiroshi Ueda, Shigeki OnodaAbstract:The Spin-$1/2$ Heisenberg chain with a ferromagnetic first-neighbor exchange coupling ${J}_{1}$ and an antiferromagnetic second-neighbor ${J}_{2}$ has a Haldane dimer ground state with an extremely small Spin Gap. Thus the ground state is readily altered by perturbations. Here, we investigate the effects of XXZ exchange magnetic anisotropy of both the easy-axis and easy-plane types and an alternation in ${J}_{1}$ on the ground state, the Spin Gap, and magnetic properties of the frustrated ferromagnetic Spin-$1/2$ chain. It is found that there are two distinct dimerized Spin-Gap phases, in one of which the Spin Gap and the magnetic susceptibility are extremely small around the SU(2) symmetric case and in the other they are moderately large far away from the SU(2) symmetric case. A small alternation in the amplitude of ${J}_{1}$ rapidly shortens the pitch of Spin correlations towards the four-Spin periodicity, as in the limit of ${J}_{1}/{J}_{2}\ensuremath{\rightarrow}0$. These effects are not sufficient to quantitatively explain overall experimentally observed magnetic properties in the quasi-one-dimensional Spin-Gapped magnetoelectric cuprate ${\mathrm{Rb}}_{2}{\mathrm{Cu}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$ that exhibits ferroelectricity stabilized by a magnetic field. Our results are also relevant to ${\mathrm{Cs}}_{2}{\mathrm{Cu}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$, where the ferromagnetic intrachain and antiferromagnetic interchain order has recently been found, in a single chain level. We also reveal the nature of symmetry-protected topological phase transitions in the model by mapping onto effective Spin-1 chain models.
-
emergent Spin 1 haldane Gap and ferroelectricity in a frustrated Spin 1 2 ladder
Physical Review B, 2020Co-Authors: Hiroshi Ueda, Shigeki Onoda, Yasutaka Yamaguchi, Tsuyoshi Kimura, Daichi Yoshizawa, T Morioka, Masayuki Hagiwara, Masato Hagihala, Minoru Soda, Takatsugu MasudaAbstract:Combined experimental and theoretical studies reveal that the low-temperature magnetic properties of Rb${}_{2}$Cu${}_{2}$Mo${}_{3}$O${}_{12}$ are nicely explained in terms of a two-leg ladder of frustrated ferromagnetic Spin-$\frac{1}{2}$ chains. The system hosts a nonmagnetic tetramer ground state that is adiabatically connected to a couple of isolated Haldane dimer Spin-$\frac{1}{2}$ chains. Remarkably, ferroelectricity emerges at much lower magnetic fields than the Spin Gap, suggesting a rare case of ferroelectricity induced by vector Spin chirality.
J M D Coey - One of the best experts on this subject based on the ideXlab platform.
-
cubic mn 2 ga thin films crossing the Spin Gap with ruthenium
Physical Review Letters, 2014Co-Authors: H Kurt, K Rode, P Stamenov, M Venkatesan, Yongchang Lau, E Fonda, J M D CoeyAbstract:Cubic Mn2Ga films with the half-Heusler C1b structure are grown on V (001) epitaxial films. The phase is a soft ferrimagnet, with Curie temperature TC = 225 K and magnetization Ms=280 kA m(-1), equivalent to 1.65μB per formula. Adding ruthenium leads to an increase of TC up to 550 K in cubic Mn2Ru(x)Ga films with x = 0.33 and a collapse of the net magnetization. The anomalous Hall effect changes sign at x = 0.5, where the sign of the magnetization changes and the magnetic easy direction flips from in plane to perpendicular to the film. The Mn2Ru0.5Ga compound with a valence electron count of 21 is identified as a zero-moment ferrimagnet with high Spin polarization, which shows evidence of half-metallicity.
-
cubic mn 2 ga thin films crossing the Spin Gap with ruthenium
Physical Review Letters, 2014Co-Authors: H Kurt, K Rode, P Stamenov, M Venkatesan, Yongchang Lau, E Fonda, J M D CoeyAbstract:Cubic ${\mathrm{Mn}}_{2}\mathrm{Ga}$ films with the half-Heusler $C{1}_{b}$ structure are grown on V (001) epitaxial films. The phase is a soft ferrimagnet, with Curie temperature ${T}_{C}\text{ }=\text{ }225\text{ }\text{K}$ and magnetization ${M}_{s}=280\text{ }\text{ }\text{kA}\text{ }{\text{m}}^{\ensuremath{-}1}$, equivalent to $1.65\phantom{\rule[-0.0ex]{0.21em}{0.0ex}}\phantom{\rule{0ex}{0ex}}{\ensuremath{\mu}}_{B}$ per formula. Adding ruthenium leads to an increase of ${T}_{C}$ up to 550 K in cubic ${\text{Mn}}_{2}{\text{Ru}}_{x}\text{Ga}$ films with $x\text{ }=\text{ }0.33$ and a collapse of the net magnetization. The anomalous Hall effect changes sign at $x\text{ }=\text{ }0.5$, where the sign of the magnetization changes and the magnetic easy direction flips from in plane to perpendicular to the film. The ${\text{Mn}}_{2}{\text{Ru}}_{0.5}\text{Ga}$ compound with a valence electron count of 21 is identified as a zero-moment ferrimagnet with high Spin polarization, which shows evidence of half-metallicity.
Qingjin Meng - One of the best experts on this subject based on the ideXlab platform.
-
crystal structures and magnetic properties of two molecular solids based on bis maleonitriledithiolate nickelate monoanion with substituted piperidinium cations
Synthetic Metals, 2010Co-Authors: Jiarong Zhou, Hongrong Zuo, Qian Huang, Yong Hou, Lemin Yang, Xing Chen, Yingying Zheng, Qingjin MengAbstract:Abstract Two new molecular solids, [1-NaMePid][Ni(mnt) 2 ] (1) and [2-NaMePid][Ni(mnt) 2 ] (2) (mnt 2− = maleonitriledithiolate, [1-NaMePid] + = 1-(1′-naphthylmethyl)piperidinium and [2-NaMePid] + = 1-(2′-naphthylmethyl)piperidinium) have been characterized structurally and magnetically. Both [Ni(mnt) 2 ] − anions and the cations of 1 and 2 form segregated column stacks, and the Ni(III) ions form a 1D zigzig alternating magnetic chain within a [Ni(mnt) 2 ] − column through Ni···S, S···S, Ni···Ni, or π···π interactions. Some conformational features in two isomeric cations and the geometry of the individual [Ni(mnt) 2 ] − anion for 1 and 2 remain similar, while the changes of the space filling properties, the packing requirements and the existence of the water molecule in 2 result in the difference of the stacking mode of the [Ni(mnt) 2 ] − anions. Magnetic susceptibility measurements in the temperature range 2–300 K show that 1 is diamagnetism, while 2 exhibits a novel and interesting Spin–Gap transition around 16.8 K with antiferromagnetic interaction ( J = −4.6 cm −1 ) in the high-temperature phase (HT) and the Spin–Gap (Δ/ k b = 68.5 K) in the low-temperature phase (LT).
-
unusual Spin Gap transition observed in two new molecular magnets based on ni mnt 2 monoanion mnt2 maleonitriledithiolate
Journal of Solid State Chemistry, 2009Co-Authors: Hongrong Zuo, Qian Huang, Chunyan Huang, Donghai Huang, Yong Hou, Lemin Yang, Qingjin MengAbstract:Two new molecular magnets, [RBzPyN(CH{sub 3}){sub 2}][Ni(mnt){sub 2}] [mnt{sup 2-}=maleonitriledithiolate; [RBzPyN(CH{sub 3}){sub 2}]{sup +}=1-(4'-R-benzyl)-4-dimethylaminopyridinium; R=CN(1), F(2)], with unusual magnetic properties have been prepared and characterized. Both 1 and 2 form a 3D network structure in which the [Ni(mnt){sub 2}]{sup -} anions form a 1D magnetic chain for 1 and a stepwise stack for 2via weak {pi}...{pi} stacking interactions, C...C or C...N short interactions between the neighboring anions. Magnetic susceptibility measurements in the temperature range 1.8-300 K indicated that 1 and 2 show unusual Spin Gap transition around 30 K and 110 K, respectively. The transition for 1 and 2 is the second-order phase transition as determined by the capacity measurement. - Graphical Abstract: Two new molecular magnets based on [Ni(mnt){sub 2}]{sup -} monoanion form a 1D magnetic chain for 1 and a stepwise stack for 2, and exhibit unusual Spin Gap transition.
-
synthesis crystal structure and magnetic property of a new 1d molecular material 1 4 chlorobenzyl 4 aminopyridinium bis maleonitriledithiolato nickel
Journal of Solid State Chemistry, 2005Co-Authors: Chunlin Ni, Dongbin Dang, Yizhi Li, Zhaoping Ni, Zhengfang Tian, Qingjin MengAbstract:Abstract A new ion-pair complex, [1-(4′-chlorobenzyl)–4-aminopyridinium](+)bis(maleonitrile-dithiolato)nickel(−),[ClbzPyNH2][Ni(mnt)2] (1), has been prepared and characterized. X-ray single crystal structure conforms that the Ni(mnt)2− anions and [ClbzPyNH2]+ cations of 1 form completely segregated uniform stacking columns with the Ni⋯Ni distance 3.944 A in the Ni(mnt)2− stacking column. The temperature dependence of the magnetic susceptibility reveals that 1 undergoes a magnetic transition, and exhibits ferromagnetic interaction in the high-temperature phase and Spin Gap system in the low-temperature phase.
Azusa Matsuda - One of the best experts on this subject based on the ideXlab platform.
-
anisotropic resistivities of precisely oxygen controlled single crystal bi2sr2cacu2o8 δ systematic study on Spin Gap effect
Physical Review Letters, 1997Co-Authors: T Watanabe, T Fujii, Azusa MatsudaAbstract:The in-plane resistivity ${\ensuremath{\rho}}_{a}(T)$ and the out-of-plane resistivity ${\ensuremath{\rho}}_{c}(T)$ have been systematically measured for ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ single crystals with their oxygen contents precisely controlled. In the underdoped region, deviation from $T$-linear in-plane resistivity, which evidences the opening of the ``Spin Gap,'' is clearly observed, while the out-of-plane resistivity is well reproduced by the activation-type phenomenological formula ${\ensuremath{\rho}}_{c}(T)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(a/T)\mathrm{exp}(\ensuremath{\Delta}/T)+c$. In contrast to the ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ system, we find that the onset of the semiconducting ${\ensuremath{\rho}}_{c}(T)$ does not coincide with the opening of the Spin Gap seen in the ${\ensuremath{\rho}}_{a}(T)$ in this ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ system.
-
anisotropic resistivities of precisely oxygen controlled single crystal bi 2 sr 2 cacu 2 o 8 δ systematic study on Spin Gap effect
Physical Review Letters, 1997Co-Authors: T Watanabe, T Fujii, Azusa MatsudaAbstract:The in-plane resistivity ${\ensuremath{\rho}}_{a}(T)$ and the out-of-plane resistivity ${\ensuremath{\rho}}_{c}(T)$ have been systematically measured for ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ single crystals with their oxygen contents precisely controlled. In the underdoped region, deviation from $T$-linear in-plane resistivity, which evidences the opening of the ``Spin Gap,'' is clearly observed, while the out-of-plane resistivity is well reproduced by the activation-type phenomenological formula ${\ensuremath{\rho}}_{c}(T)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(a/T)\mathrm{exp}(\ensuremath{\Delta}/T)+c$. In contrast to the ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ system, we find that the onset of the semiconducting ${\ensuremath{\rho}}_{c}(T)$ does not coincide with the opening of the Spin Gap seen in the ${\ensuremath{\rho}}_{a}(T)$ in this ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ system.