When an electron passes through a chiral molecule, there is a high probability for correlation between the momentum and spin of the charge, thus leading to a spin polarized current. This phenomenon is known as the chiralinduced spin selectivity (CISS) effect. One of the most surprising experimental results recently demonstrated is that magnetization reversal in a ferromagnet with perpendicular anisotropy can be realized solely by chemisorbing a chiral molecular monolayer without applying any current or external magnetic field. This result raises the currently open question of whether this effect is due to the bonding event, held by the ferromagnet, or a long-time-scale effect stabilized by exchange interactions. In this work we have performed vectorial magnetic field measurements of the magnetization reorientation of a ferromagnetic layer exhibiting perpendicular anisotropy due to CISS using nitrogen-vacancy centers in diamond and followed the time dynamics of this effect. In parallel, we have measured the molecular monolayer tilt angle in order to find a correlation between the time dependence of the magnetization reorientation and the change of the tilt angle of the molecular monolayer. We have identified that changes in the magnetization direction correspond to changes of the molecular monolayer tilt angle, providing evidence for a long-time-scale characteristic of the induced magnetization reorientation. This suggests that the CISS effect has an effect over long time scales which we attribute to exchange interactions. These results offer significant insights into the fundamental processes underlying the CISS effect, contributing to the implementation of CISS in state-of-the-art applications such as spintronic and magnetic memory devices.

Magnetization in rock samples is crucial for paleomagnetometry research, as it harbors valuable geological information on long term processes, such as tectonic movements and the formation of oceans and continents. Nevertheless, current techniques are limited in their ability to measure high spatial resolution and high-sensitivity quantitative vectorial magnetic signatures from individual minerals and micrometer scale samples. As a result, our understanding of bulk rock magnetization is limited, specifically for the case of multi-domain minerals. In this work we use a newly developed nitrogen-vacancy magnetic microscope, capable of quantitative vectorial magnetic imaging with optical resolution. We demonstrate direct imaging of the vectorial magnetic field of a single, multi-domain dendritic magnetite, as well as the measurement and calculation of the weak magnetic moments of an individual grain on the micron scale. These results pave the way for future applications in paleomagnetometry, and for the fundamental understanding of magnetization in multi-domain samples.When igneous rocks in Earth's crust are formed by cooling of hot magma they acquire thermoremanent magnetization (TRM) parallel and proportional to the ambient field at the time of cooling. TRM can remain stable for millions of years preserving valuable geological magnetic information on complex long term processes, such as plate tectonic movements and formations of oceans and continents [1]. Despite its importance, little is known on the details of how thermoremanent magnetic information is acquired and retained in rocks [2]. Paleomagnetism, the science of studying natural magnetic information, heavily relies on Néel theory [3] of single-domain (SD) minerals. Yet, the dimensions of rock-forming minerals typically exceed the sub-micrometric threshold size for SD. As such, TRM is mostly held by multi-domain (MD) particles rather than by SD. In the absence of a general analytical formulation for TRM in MD, there is a growing need for direct observations of natural MD magnetization. Particularly, vectorial imaging of magnetic fields generated by MD particles with sub-micron spatial resolution and micrometer scale sample-detector distance, along with high sensitivity (µT / √ Hz), is critical for understanding the mechanism controlling the geometry and size of MD arrangements, the total moment exerted by individual natural crystals, and the stability of MD magnetic information over geological times.There are a number of magnetic imaging techniques that have been used in paleomagnetic research in a complementary fashion: Kerr effect [4] , Magnetic Force Microscopy (MFM) [5], electron holography [6], and SQUID microscopy [7]. Recently, a newly developed method based on nitrogen-vacancy (NV) magnetic microscopy [8][9][10], has been demonstrated by [11,12] in the context of paleomagnetometry. NV magnetic microscopy enables direct measurements of the three components of the magnetic field vector at a constant height above the sample in a room temperature environ...

Nitrogen-vacancy (NV) color centers in diamond have been demonstrated as useful magnetic sensors, in particular for measuring spin fluctuations and achieving high sensitivity and spatial resolution. These abilities can be used to explore various biological and chemical processes, catalyzed by reactive oxygen species (ROS). Here we demonstrate a novel approach to measure and quantify hydroxyl radicals with high spatial resolution, using the fluorescence difference between NV charged states. According to the results, the achieved NV sensitivity is ± 11 4 nM Hz , realized in situ without spin labels and localized to a volume of ∼10 picoliters.

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