Manipulating Berry curvature of SrRuO₃thin films via epitaxial strain

Abstract

Berry curvature plays a crucial role in exotic electronic states of quantum materials, such as the intrinsic anomalous Hall effect. As Berry curvature is highly sensitive to subtle changes of electronic band structures, it can be finely tuned via external stimulus. Here, we demonstrate in SrRuO3 thin films that both the magnitude and sign of anomalous Hall resistivity can be effectively controlled with epitaxial strain. Our first-principles calculations reveal that epitaxial strain induces an additional crystal field splitting and changes the order of Ru d orbital energies, which alters the Berry curvature and leads to the sign and magnitude change of anomalous Hall conductivity. Furthermore, we show that the rotation of the Ru magnetic moment in real space of a tensile-strained sample can result in an exotic nonmonotonic change of anomalous Hall resistivity with the sweeping of magnetic field, resembling the topological Hall effect observed in noncoplanar spin systems. These findings not only deepen our understanding of anomalous Hall effect in SrRuO3 systems but also provide an effective tuning knob to manipulate Berry curvature and related physical properties in a wide range of quantum materials.

Genetic inactivation of SARM1 axon degeneration pathway improves outcome trajectory after experimental traumatic brain injury based on pathological, radiological, and functional measures

“…Mitochondrial stress, trauma or other insults lead to loss of nicotinamide mononucleotide adenylyl-transferase 2 (NMNAT2), an NAD-synthesizing enzyme, in axons that depletes NAD + and raises the level of its precursor nicotinamide mononucleotide (NMN) [ 21 , 48 ]. Low NAD + and high NMN levels regulate release of auto-inhibition of SARM1 NADase activity, which further depletes NAD + and axon energy stores [ 12 , 22 , 39 , 76 , 80 ]. Axons with swollen mitochondria were significantly increased at 3 days after TBI in Sarm1 WT and Sarm1 KO mice [ 52 ].…”

“…Wallerian degeneration is an “active program of axon self-destruction” [ 76 ]. After injury or mitochondrial dysfunction, the SARM1 (sterile alpha and Toll/interleukin-1 receptor motif-containing 1) protein executes a highly conserved molecular axon degeneration pathway [ 27 , 48 , 70 , 84 ].…”

“…After injury or mitochondrial dysfunction, the SARM1 (sterile alpha and Toll/interleukin-1 receptor motif-containing 1) protein executes a highly conserved molecular axon degeneration pathway [ 27 , 48 , 70 , 84 ]. Injury releases SARM1 from an auto-inhibited state that is found in healthy axons [ 22 , 76 , 80 ]. Active SARM1 is a glycohydrolase which depletes nicotinamide adenine dinucleotide (NAD +) that is critical for energy stores in axons [ 18 , 23 , 26 ].…”

A Generic Sacrificial Layer for Wide‐Range Freestanding Oxides with Modulated Magnetic Anisotropy

“…These features suggest SCO as a promising sacrificial material for obtaining high-quality complex oxide nanomembranes. We focused on ferromagnetic metallic SrRuO 3 (SRO) as a freestanding material in this study (Figure 1a), the structurally correlated magnetic anisotropy [11,21,[25][26][27] and strong intrinsic spinorbit coupling [28] of which ensure scientific interest and the technical importance of exploring its nanomembranes.…”

Strain engineering of electronic properties and anomalous valley hall conductivity of transition metal dichalcogenide nanoribbons

“…Furthermore, the Bloch state |nk > of Berry curvature i.e. become 69 : in this equation, is the periodic part of Bloch state |nk > . The Kubo-like formula is used to calculate Berry curvature as: Where is a complex velocity, and and are both empty or filled up.…”