import matplotlib.pyplot as plt
import numpy as np
from matplotlib.ticker import AutoMinorLocator

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

x = np.linspace(1, 10, 100)
y = np.log(x)

fig, ax = plt.subplots()
ax.plot(x, y)
minor_locator = AutoMinorLocator(2)
ax.xaxis.set_minor_locator(minor_locator)
plt.grid(which='minor')

plt.show()