Figure 2.

The in-plane Hall coefficient R_H of YBCO crystals measured in samples 1–3 with y = 6.23, 6.30, and 6.36, respectively. In sample 1, R_H attains a broad maximum near the Néel temperature T_N and decreases by ≈50 below 70 K. Samples 2 and 3 have a similar behavior except that the low T values are not as strongly suppressed. A slight minimum (“notch”) occurs near T_N in 2 and 3, but not in 1. In each curve, the high-density data above 250 K were taken by using a technique of alternating the current and voltage contacts with H fixed at 14 T. Data with wider spacing were taken by slowly scanning the field between −8 and +8 T and back at fixed T.