arXiv subjects

P. A. Algarabel

Publications and source records attributed to P. A. Algarabel.

8 recordsLinked to original sources

arXiv2026

Independent Tuning of Surface Acoustic-Waves and Spin-Waves via Buffer-Layer Engineering in Co2FeGe Heusler Thin Films

Understanding and controlling acoustic and spin-wave excitations in magnetic thin films is critical for the development of magnonic and spin-acoustic devices. We report on the use of Cr and W buffer layers to independently modify the acoustic and magnetic excitations in Co2FeGe full-Heusler thin films grown on MgO(001). Using Brillouin light scattering (BLS) spectroscopy and ferromagnetic resonance (FMR), we probed Rayleigh and Sezawa surface acoustic waves (SAWs) alongside Damon-Eshbach and perpendicular standing spin-wave (PSSW) modes. Our results show that acoustic dispersion depends strongly on the buffer material; W-buffered films exhibit a pronounced 16% reduction in Rayleigh SAW frequency compared to buffer-free films, primarily due to mass loading and acoustic impedance shifts. While the buffer layers significantly shift acoustic frequencies, they simultaneously modify the dynamic magnetic response (increasing spin-wave group velocity by ~34%) through different physical mechanisms. Finite-element simulations show excellent agreement with the experimental acoustic data. These findings demonstrate that buffer-layer engineering is an effective strategy for the independent tailoring of elastic and magnetic excitations, providing a versatile platform for hybrid spin-acoustic technologies.

cond-mat.mtrl-sci↗

arXiv2025

Spin waves in Co$_2$FeGe films

The dynamic magnetic properties of Full Heusler alloy thin films of Co$_2$FeGe, grown on MgO (001) substrates under different thermal conditions, were investigated. Brillouin light scattering and ferromagnetic resonance measurements revealed that depositing at room temperature followed by annealing at 300 deg C for 1 hour produces the best results for maximizing magnetization, exchange stiffness, and minimizing spin-dynamic dissipation in the films, which are desirable characteristics for high-speed spintronic devices. Additionally, strong hybridization of spin waves in the Damon-Eshbach geometry was observed, which is attractive for applications in magnonic signal processing circuits.

cond-mat.mtrl-sci↗

arXiv2021

Terahertz spin currents and inverse spin Hall effect in thin-film heterostructures containing complex magnetic compounds

Terahertz emission spectroscopy of ultrathin multilayers of magnetic and heavy metals has recently attracted much interest. This method not only provides fundamental insights into photoinduced spin transport and spin-orbit interaction at highest frequencies but has also paved the way to applications such as efficient and ultrabroadband emitters of terahertz electromagnetic radiation. So far, predominantly standard ferromagnetic materials have been exploited. Here, by introducing a suitable figure of merit, we systematically compare the strength of terahertz emission from X/Pt bilayers with X being a complex ferro-, ferri- and antiferromagnetic metal, that is, dysprosium cobalt (DyCo$_5$), gadolinium iron (Gd$_{24}$Fe$_{76}$), Magnetite (Fe$_3$O$_4$) and iron rhodium (FeRh). We find that the performance in terms of spin-current generation not only depends on the spin polarization of the magnet's conduction electrons but also on the specific interface conditions, thereby suggesting terahertz emission spectroscopy to be a highly surface-sensitive technique. In general, our results are relevant for all applications that rely on the optical generation of ultrafast spin currents in spintronic metallic multilayers.

cond-mat.mtrl-sci↗

arXiv2018

Interface-induced anomalous Nernst effect in Fe3O4/Pt-based heterostructures

We have studied the anomalous Nernst effect (ANE) in [Fe3O4/Pt]-based heterostructures, by measuring the ANE-induced electric field with a magnetic field applied normal to the sample surface, in the perpendicular magnetized configuration, where only the ANE is expected. An ANE voltage is observed for [Fe3O4/Pt]n multilayers, and we further investigated its origin by performing measurements in [Fe3O4/Pt/Fe3O4] trilayers as a function of the Pt thickness. Our results suggest the presence of an interface-induced ANE. Despite of this ANE, the spin Seebeck effect is the dominant mechanism for the transverse thermoelectric voltage in the in-plane magnetized configuration, accounting for about 70 % of the measured voltage in the multilayers.

cond-mat.mtrl-sci↗

arXiv2016

Thermoelectric performance of spin Seebeck effect in Fe3O4/Pt-based thin film heterostructures

We report a systematic study on the thermoelectric performance of spin Seebeck devices based on Fe3O4/Pt junction systems. We explore two types of device geometries: a spin Hall thermopile and spin Seebeck multilayer structures. The spin Hall thermopile increases the sensitivity of the spin Seebeck effect, while the increase in the sample internal resistance has a detrimental effect on the output power. We found that the spin Seebeck multilayers can overcome this limitation since the multilayers exhibit the enhancement of the thermoelectric voltage and the reduction of the internal resistance simultaneously, therefore resulting in significant power enhancement. This result demonstrates that the multilayer structures are useful for improving the thermoelectric performance of the spin Seebeck effect.

cond-mat.mtrl-sci↗

arXiv2015

Observation of huge thermal spin currents in magnetic multilayers

Thermal spin pumping constitutes a novel mechanism for generation of spin currents; however their weak intensity constitutes a major roadblock for its usefulness. We report a phenomenon that produces a huge spin current in the central region of a multilayer system, resulting in a giant spin Seebeck effect in a structure formed by repetition of ferromagnet/metal bilayers. The result is a consequence of the interconversion of magnon and electron spin currents at the multiple interfaces. This work opens the possibility to design thin film heterostructures that may boost the application of thermal spin currents in spintronics.

cond-mat.mtrl-sci↗

arXiv2007

Mesoscopic Magnetic States in Metallic Alloys with Strong Electronic Correlations: A Percolative Scenario for CeNi$_{1-x}$Cu$_{x}$

We present evidence for the existence of magnetic clusters of approximately 20 Åin the strongly correlated alloy system CeNi$_{1-x}$Cu$_{x}$ (0.7 $\le$ x $\le$ 0.2) based on small angle neutron scattering experiments as well as the occurrence of staircase-like hysteresis cycles during very low temperature (100 mK) magnetization measurements. An unusual feature is the observation of long-range ferromagnetic order below the cluster-glass transition without any indication of a sharp transition at a Curie temperature. These observations strongly support a phenomenological model where a percolative process connects the cluster-glass state observed at high temperatures with the long-range ferromagnetic order observed by neutron diffraction experiments at very low temperatures. The model can account for all the puzzling macroscopic and microscopic data previously obtained in this system, providing a new perspective with regard to the magnetic ground state of other alloyed compounds with small magnetic moments or weak ferromagnetism with intrinsic disorder effects.

cond-mat.str-el↗

arXiv2001

Magnetic-field -induced structural changes in the electron doped manganites: CaxSm1-xMnO3 (x = 0.8, 0.85)

We studied the correlation between magnetic, electrical, structural, and magnetostriction properties of the electron doped manganites Ca$_x$Sm$_{1-x}$MnO$_3$ (x = 0.85, 0.8). The paramagnetic to antiferromagnetic transition in both the compounds while cooling is accompanied by an abrupt increase of the spontaneous volume thermal expansion ($Δ$V/V = 0.07 % for x = 0.85 and 0.25 % for x = 0.2). The x = 0.15 exhibits multiple phase separation at 5 K: G-type, and C-type antiferromagnetic phases in orthorhombic (\QTR{it}{Pnma}) and monoclinic (\QTR{it}{P2}$_1$\QTR{it}{/m}) structures respectively. Magnetic study on x = 0.85 also suggest ferromagnetic regions possibly in $Pnma$ structure coexist with the antiferromagnetic phases. The magnetization (M = 1.2 $μ_B$) of x = 0.85 does not reach the value expected for the complete alignment of Mn spins even at 12 T and at 12 K. Metamagnetic transitions (C-type to Ferromagnetic) in both compounds are accompanied by contraction of volumes under high magnetic fields. We suggest that a high magnetic field induces \QTR{it}{P2}$_1$\QTR{it}{/m} (high volume) to \QTR{it}{Pnma} (low volume) structural transition. This is also supported by the neutron diffraction study.

cond-mat.mtrl-sci↗