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Research on ultrathin magnetic layers and layered materials has reached an enormous impact, both scientifically and economically, with respect to applications in magnetic data storage technology, as sensors, or for future electronics utilizing the spin rather than the charge of electrons, the so-called "spintronics". [1][2][3][4] The physical size of a bit of information in magnetic data storage is already in the nanometer regime and is still shrinking, following the everincreasing demand for higher recording densities. Very soon the dimension of the recording bit will reach the sub-10 nm range. This poses formidable challenges to the read sensors. One ingredient of hard disk read sensors are magnetic layered systems in which ferromagnetic (FM) and antiferromagnetic (AFM) materials are in contact. [5] They show the exchange bias (EB) effect, which has received increased attention during the past decades. [6][7][8][9][10][11] It manifests itself in a shift of the magnetic hysteresis loop of the FM layer along the field axis. [12] Although reported first in 1956, [13] it was only in the mid-1990s that it shifted into the center of interest, triggered by applications of FM/AFM heterostructures for tailoring the magnetic properties of magnetoresistive devices. The past years have seen significant advances toward an explanation of the effect, however, a fundamental microscopic picture of the origin of the unidirectional magnetic anisotropy present in the EB effect is still missing.The occurrence of EB requires two basic ingredients: a magnetic interaction between FM and AFM spins at the interface, and a pinning of magnetic moments against the reversal of the FM-layer magnetization by the external magnetic field inside the AFM layer. As in AFM materials the direction of the spins varies on the length scale of single atomic distances, a thorough characterization of the atomic structure of the films and their interface is mandatory for fundamental investigations into the effect. In the commonly used polycrystalline systems prepared by sputtering techniques this is naturally not the case. A promising approach is the investigation of single-crystalline systems. [14][15][16][17][18][19] In such systems, it is shown, for example, that the magnetic coupling between AFM and FM layers is due to

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Single‐crystalline antiferromagnetic artificially layered [Ni/Mn] films of different thicknesses, covered by ferromagnetic Co layers, are deposited on . Their structural and magnetic properties are characterized by low‐energy electron diffraction (LEED) and magneto‐optical Kerr effect, respectively, and compared with disordered alloy films with the same Ni/Mn ratio and the same film thickness. LEED intensity‐versus‐energy curves show that the perpendicular interatomic lattice distance is decreased in the artificially layered [Ni/Mn] samples in comparison to the disordered alloy films. At the same time, the artificially layered [Ni/Mn] films exhibit higher coercivity and exchange bias of the adjacent Co layer compared to those of . This is discussed as a consequence of the different interatomic lattice distance, presumably caused by an ordered buckling in the artificially layered [Ni/Mn] samples, leading to a stronger interlayer exchange coupling.