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Register a new userEffect of uniaxial stress on the magnetic phases of CeAuSb$_2$
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We present results of measurements of resistivity of CAS{} under the combination of $c$-axis magnetic field and in-plane uniaxial stress. In unstressed CAS{} there are two magnetic phases. The low-field A phase is a single-component spin-density wave (SDW), with $mathbf{q} = (eta, pm eta, 1/2)$, and the high-field B phase consists of microscopically coexisting $(eta, eta, 1/2)$ and $(eta, -eta, 1/2)$ spin-density waves. Pressure along a $langle 100 rangle$ lattice direction is a transverse field to both of these phases, and so initially has little effect, however eventually induces new low- and high-field phases in which the principal axes of the SDW components appear to have rotated to the $langle 100 rangle$ directions. Under this strong $langle 100 rangle$ compression, the field evolution of the resistivity is much smoother than at zero strain: In zero strain, there is a strong first-order transition, while under strong $langle 100 rangle$ it becomes much broader. We hypothesize that this is a consequence of the uniaxial stress lifting the degeneracy between the (100) and (010) directions.
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We study the response of the antiferromagnetism of CeAuSb$_2$ to orthorhombic lattice distortion applied through in-plane uniaxial pressure. The response to pressure applied along a $langle 110 rangle$ lattice direction shows a first-order transition at zero pressure, which shows that the magnetic order lifts the $(110)/(1bar{1}0)$ symmetry of the unstressed lattice. Sufficient $langle 100 rangle$ pressure appears to rotate the principal axes of the order from $langle 110 rangle$ to $langle 100 rangle$. At low $langle 100 rangle$ pressure, the transition at $T_N$ is weakly first-order, however it becomes continuous above a threshold $langle 100 rangle$ pressure. We discuss the possibility that this behavior is driven by order parameter fluctuations, with the restoration of a continuous transition a result of reducing the point-group symmetry of the lattice.
The nature of competition between incommensurate (IC) and commensurate (C) antiferromagnetic (AF) orders in UPd2Si2 was investigated by performing elastic neutron scattering experiments under uniaxial stress sigma. It is found that applying sigma along tetragonal [010] direction reduces the IC-AF order, and then stabilizes the C-AF order. The transition temperature from IC- to C-AF phases T_Nl is enhanced from 109 K (sigma=0) to 112.5 K (0.8 GPa), while the onset of IC-AF transition T_Nh is unchanged from 132 K under sigma. In addition, c-axis component q_z of the IC-AF modulation at 115 K also increases from 0.736 (sigma=0) to 0.747 (0.8 GPa). The magnitude of C-AF moment at 5 K is estimated to be 2.2 mu_B/U in the entire sigma range presently investigated (sigma <= 0.8 GPa). These features are similar to those obtained from the investigations using hydrostatic pressure p, indicating that applications of p and sigma||[010] commonly induce the crystal strains which inherently affect a delicate balance of frustrated magnetic interactions between uranium 5f moments.
The Weyl semimetal NbP exhibits a very small Fermi surface consisting of two electron and two hole pockets, whose fourfold degeneracy in $k$ space is tied to the rotational symmetry of the underlying tetragonal crystal lattice. By applying uniaxial stress, the crystal symmetry can be reduced, which successively leads to a degeneracy lifting of the Fermi-surface pockets. This is reflected by a splitting of the Shubnikov-de Haas frequencies when the magnetic field is aligned along the $c$ axis of the tetragonal lattice. In this study, we present the measurement of Shubnikov-de Haas oscillations of single-crystalline NbP samples under uniaxial tension, combined with state-of-the-art calculations of the electronic band structure. Our results show qualitative agreement between calculated and experimentally determined Shubnikov-de Haas frequencies, demonstrating the robustness of the band-structure calculations upon introducing strain. Furthermore, we predict a significant shift of the Weyl points with increasing uniaxial tension, allowing for an effective tuning to the Fermi level at only 0.8% of strain along the $a$ axis.
The effect of uniaxial pressure (P_u) on the magnetic susceptibility (X), magnetization (M), and magnetoresistance (MR) of the heavy-fermion metamagnet CeRu2Si2 has been investigated. For the magnetic field along the tetragonal c axis, it is found that characteristic physical quantities, i.e., the temperature of the susceptibility maximum (T_max), the pagamagnetic Weiss temperature (Q_p), 1/X at 2 K, and the magnetic field of the metamagnetic anomaly (H_M), scale approximately linearly with P_u, indicating that all the quantities are related to the same energy scale, probably of the Kondo temperature. The increase (decrease) of the quantities for P_u || c axis (P_u || a axis) can be attributed to a decrease (increase) in the nearest Ce-Ru distance. Consistently in MR and X, we observed a sign that the anisotropic nature of the hybridization, which is believed to play an important role in the metamagnetic anomaly, can be controlled by applying the uniaxial pressure. PACS numbers: 75.20.Hr, 71.27.+a, 74.62.Fj
We report the discovery of a field driven transition from a striped to woven Spin Density Wave (SDW) in the tetragonal heavy fermion compound CeAuSb$_2$. Polarized along $bf c$, the sinusoidal SDW amplitude is 1.8(2) $mu_B$/Ce for $T ll T_N$=6.25(10) K with wavevector ${bf q}_{1}=( eta, eta, frac{1}{2} )$ ($eta=0.136(2)$). For ${bf H}parallel{bf c}$, harmonics appearing at $2{bf q}_{1}$ evidence a striped magnetic texture below $mu_circ H_{c1}=2.78(1)$ T. Above $H_{c1}$, these are replaced by woven harmonics at ${bf q}_{1}+{bf q}_2=(2eta, 0, 0)+{bf c}^*$ until $mu_circ H_{c2}=5.42(5)$ T, where satellites vanish and magnetization non-linearly approaches saturation at 1.64(2) $mu_B$/Ce for $mu_circ Happrox 7$ T.
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